busdma: Remove outdated comments about Giant.

MFC after:	2 weeks

sys/arm/arm/busdma_machdep.c

@@ -419,9 +419,7 @@ must_bounce(bus_dma_tag_t dmat, bus_dmamap_t map, bus_addr_t paddr,
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)

sys/arm64/arm64/busdma_machdep.c

@@ -53,9 +53,7 @@ __FBSDID("$FreeBSD$");
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)

sys/mips/mips/busdma_machdep.c

@@ -298,9 +298,7 @@ _bus_dma_can_bounce(vm_offset_t lowaddr, vm_offset_t highaddr)
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)

sys/powerpc/powerpc/busdma_machdep.c

@@ -186,9 +186,7 @@ run_filter(bus_dma_tag_t dmat, bus_addr_t paddr)
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)

sys/riscv/riscv/busdma_machdep.c

@@ -53,9 +53,7 @@ __FBSDID("$FreeBSD$");
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)

sys/x86/x86/busdma_machdep.c

@@ -57,9 +57,7 @@ __FBSDID("$FreeBSD$");
 
 /*
  * Convenience function for manipulating driver locks from busdma (during
- * busdma_swi, for example).  Drivers that don't provide their own locks
- * should specify &Giant to dmat->lockfuncarg.  Drivers that use their own
- * non-mutex locking scheme don't have to use this at all.
+ * busdma_swi, for example).
  */
 void
 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)