driver: staging: count ashmem_range into SLAB_RECLAIMBLE

Add SLAB_RECLAIM_ACCOUNT to ashmem_range cache since it has registered
shrinker, which make memAvailable more presiced.

Acked-by: Todd Kjos <tkjos@google.com>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Link: https://lore.kernel.org/r/1608277668-3740-1-git-send-email-huangzhaoyang@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>