Selinux: Give lmkd read access to /proc/meminfo

Allow lmkd read access to /proc/meminfo for retrieving information
on memory state.

Change-Id: I7cf685813a5a49893c8f9a6ac4b5f6619f3c18aa
Signed-off-by: Suren Baghdasaryan <surenb@google.com>