x86/asm: Have the __ASM_FORM macros handle commas in arguments

The __ASM_FORM macros are really useful, but in order to be able to
use them to define instructions via .byte directives breaks because of
the necessary commas. Change the macros to handle commas correctly.

[ mingo: Removed stray whitespaces & aligned the definitions vertically. ]

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210510090940.924953-2-hpa@zytor.com