lib/genalloc.c: Fix a typo

s/macthing/matching/

Link: https://lkml.kernel.org/r/20210326131530.30481-1-unixbhaskar@gmail.com


Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>