boot1.chrp: Improve comment for the SLOF hack

Since this original comment was written, the actual issue in SLOF
was diagnosed and documented in commit 424089a0fc, which fixed it
for loader(8).  Update the comment in boot1 to be more informative
to future readers.

MFC after:	3 days
Reviewed by:	jhibbits, adrian
Sponsored by:	https://www.patreon.com/bsdivy
Differential Revision:	https://reviews.freebsd.org/D56470

stand/powerpc/boot1.chrp/boot1.c

@@ -102,14 +102,11 @@ ofwh_t bootdevh;
 ofwh_t stdinh, stdouth;
 
 /*
- * Note about the entry point:
+ * Our entrypoint.
  *
- * For some odd reason, the first page of the load appears to have trouble
- * when entering in LE. The first five instructions decode weirdly.
- * I suspect it is some cache weirdness between the ELF headers and .text.
- *
- * Ensure we have a gap between the start of .text and the entry as a
- * workaround.
+ * A bug in the SLOF shipped with some versions of QEMU causes the first
+ * 32 bytes of .text to be wrongly byte-swapped when loading LE programs.
+ * As a workaround, we add some padding at the start of the text section.
  */
 __asm("                         \n\
         .data                   \n\
@@ -118,7 +115,7 @@ stack:                          \n\
         .space  16384           \n\
                                 \n\
         .text                   \n\
-        /* SLOF cache hack */   \n\
+        /* SLOF workaround */   \n\
         .space 4096             \n\
         .globl  _start          \n\
 _start:                         \n\