The "mp" pointer is the same as "sc->mp" so this change doesn't affect
runtime at all.  However, it's nicer to use same name for both the lock
and the unlock.
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>