zram: rename zram_free_page()

zram: rename zram_free_page()

We don't free page in zram_free_page(), not all slots even have any memory
associated with them (e.g.  ZRAM_SAME).  We free the slot (or reset it),
rename the function accordingly.

Link: https://lkml.kernel.org/r/20251201094754.4149975-6-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: David Stevens <stevensd@google.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Richard Chang <richardycc@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>