ANDROID: uid_sys_stat: split the global lock uid_lock to the fine-grained

locks for each hlist in hash_table.

1.Hash_table in uid_sys_stat is protected by a global lock named id_lock,
which causes some lock competition issue. Actually, uid_lock can be split to
several file-grained locks for each hlist in hash_table, which avoid
the unnecessary lock competition when get different-uid process info.

2. Switching rt-mutex to spinlock, in order to operate with read_rcu_lock.

Bug: 278138377
Signed-off-by: Peifeng Li <lipeifeng@oppo.com>
Change-Id: Ib252b65e9aebe3a594e6edf075f7aa01f8e6105d