ACPICA: Avoid null pointer dereference on Op.

ACPICA commit 08a00639b0d6756e8ba1421419fc3728904651d9

The calls to acpi_os_acquire_object can result in a null being assigned
to Op (for example if a mutex acquire fails) which can lead to a
null pointer dereference on Op on the call to ASL_CV_TRANSFER_COMMENTS
(via function cv_transfer_comments). Move the block into the previous
block that checks for a null Op so that we never can call
cv_transfer_comments with a null Op.

Detected by: coverity_scan CID#1371660 ("Dereference after null check")

Link: https://github.com/acpica/acpica/commit/08a00639


Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>