arch/x86/syscall: Remove TODO comment

nolibc support for x86 32-bit has been added in commit b7d8dd8bbf5b855
("arch/x86/syscall: Add x86 32-bit native syscall support"). But I
forgot to remove the comment that says "We can't use CONFIG_NOLIBC for
x86 (32-bit)".

Remove it.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Link: https://lore.kernel.org/r/20220421075205.98770-1-ammar.faizi@intel.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>