kvfree(): fix misleading comment

kvfree(): fix misleading comment

vfree() might sleep if called not in interrupt context.  So does kvfree()
too.  Fix misleading kvfree()'s comment about allowed context.

Link: http://lkml.kernel.org/r/20180914130512.10394-1-aryabinin@virtuozzo.com
Fixes: 2d5130fb77dd ("mm/util.c: improve kvfree() kerneldoc")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>