ofed: reduce usage of struct dma_attrs *dma_attrs

ib_verbs.h still uses struct dma_attrs *dma_attrs everywhere.
It is beyond my knowledge when that struct got deprecated upstream but
it is still supported by our LinuxKPI.  The problem is that the
functions called with that argument (dma_map_single_attrs,
dma_unmap_single_attrs, dma_map_sg_attrs, dma_unmap_sg_attrs) so far
are #defines in LinuxKPI and drop the last argument (attrs) so it was
never a problem.

In preparation to pass the attrs to the actual implementation in LinuxKPI,
which has gained support for them, we now pass dma_sttrs->flags which
is the expected unsigned long bit field.

If anyone has serious interest in updating our ofed implementation they
could look into this some more and remove the usage of struct dma_attrs
entirely.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Reviewed by:	kib
Differential Revision: https://reviews.freebsd.org/D55390

sys/ofed/include/rdma/ib_verbs.h

@@ -3539,7 +3539,7 @@ static inline u64 ib_dma_map_single_attrs(struct ib_device *dev,
 					  struct dma_attrs *dma_attrs)
 {
 	return dma_map_single_attrs(dev->dma_device, cpu_addr, size,
-				    direction, dma_attrs);
+				    direction, dma_attrs->flags);
 }
 
 static inline void ib_dma_unmap_single_attrs(struct ib_device *dev,
@@ -3548,7 +3548,7 @@ static inline void ib_dma_unmap_single_attrs(struct ib_device *dev,
 					     struct dma_attrs *dma_attrs)
 {
 	return dma_unmap_single_attrs(dev->dma_device, addr, size,
-				      direction, dma_attrs);
+				      direction, dma_attrs->flags);
 }
 
 /**
@@ -3630,7 +3630,7 @@ static inline int ib_dma_map_sg_attrs(struct ib_device *dev,
 						  dma_attrs);
 	else
 		return dma_map_sg_attrs(dev->dma_device, sg, nents, direction,
-					dma_attrs);
+					dma_attrs->flags);
 }
 
 static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
@@ -3643,7 +3643,7 @@ static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
 						  dma_attrs);
 	else
 		dma_unmap_sg_attrs(dev->dma_device, sg, nents, direction,
-				   dma_attrs);
+				   dma_attrs->flags);
 }
 /**
  * ib_sg_dma_address - Return the DMA address from a scatter/gather entry