UPSTREAM: mm/damon/core-test: fix wrong expectations for 'damon_split_regions_of()'

Kunit test cases for 'damon_split_regions_of()' expects the number of
regions after calling the function will be same to their request
('nr_sub').  However, the requested number is just an upper-limit,
because the function randomly decides the size of each sub-region.

This fixes the wrong expectation.

Link: https://lkml.kernel.org/r/20211028090628.14948-1-sj@kernel.org


Fixes: 17ccae8b ("mm/damon: add kunit tests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

(cherry picked from commit 2e014660)

Bug: 228223814
Signed-off-by: Hailong Tu <tuhailong@oppo.com>
Change-Id: I3237d82880ca4308dd4161de9dd957925384a333