genksyms: keywords: Use __restrict not _restrict

Use the proper form of the RESTRICT keyword.

Quote the comments properly too.

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>