arm64/sve: Add a comment documenting the binutils needed for SVE asm

At some point it would be nice to avoid the need to manually encode SVE
instructions, add a note of the binutils version required to save looking
it up.

Signed-off-by: Mark Brown <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: broonie

arch/arm64/include/asm/fpsimdmacros.h

@@ -94,6 +94,7 @@
 .endm
 
 /* SVE instruction encodings for non-SVE-capable assemblers */
+/* (pre binutils 2.28, all kernel capable clang versions support SVE) */
 
 /* STR (vector): STR Z\nz, [X\nxbase, #\offset, MUL VL] */
 .macro _sve_str_v nz, nxbase, offset=0