mm/huge_memory.c: reduce critical section protected by split_queue_lock

mm/huge_memory.c: reduce critical section protected by split_queue_lock

split_queue_lock protects data in struct deferred_split.  We can release
the lock after delete the page from deferred_split_queue.

This patch moves the THP accounting out of the lock protection, which is
introduced in commit 1311b8087521 ("mm, rmap: account shmem thp pages").

Link: http://lkml.kernel.org/r/20200110025516.23996-1-richardw.yang@linux.intel.com
Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>