mm/damon: unify address range representation with damon_addr_range

mm/damon: unify address range representation with damon_addr_range

Currently, DAMON defines two identical structures for representing address
ranges: damon_system_ram_region and damon_addr_range.  Both structures
share the same semantic interpretation of a half-open interval [start,
end), where the start address is inclusive and the end address is
exclusive.

This duplication adds unnecessary redundancy and increases maintenance
overhead.  This patch replaces all uses of damon_system_ram_region with
the more generic damon_addr_range structure, ensuring a unified type
representation for address ranges within the DAMON subsystem.  The change
simplifies the codebase, improves readability, and avoids potential
inconsistencies in future modifications.

Link: https://lkml.kernel.org/r/20260129100845.281734-1-lienze@kylinos.cn
Signed-off-by: Enze Li <lienze@kylinos.cn>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>