mm/damon/core: simplify the parameter passing for region split operation

The parameter 'struct damon_ctx *ctx' is unnecessary in damon region split
operation, so we can remove it.

Link: https://lkml.kernel.org/r/1660403943-29124-1-git-send-email-kaixuxia@tencent.com


Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>