Use scoped resource management to replace open-coded locking operation
is recommended. CXL subsystem still remains some down_read()/up_read()
and down_write()/up_write() which can be replaced by guard() simply.
This patchset includes simply using guard() instead of some
down_read()/up_read() and down_write()/up_write() cases. Besides, it
also includes some function code cleanup after using guard().