misc: uidstat: Use single_release for uid_stat_read_atomic_int_fops

Currently uid_stat_read_atomic_int_fops is using the single_open
and seq_release for release callback instead single_release.
Due to this memory allocated for seq_operations struct is getting
leaked. So change the uid_stat_read_atomic_int_fops definition
to use single_release instead of seq_release callback.

Change-Id: Icd52ae094dff289a7d1c7fecee47d7ef2ed2784e
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>