mdss: mdp: avoid panic if recovery handler is uninitialized

Recovery handler is uninitialized during ctl stop process.
A fifo error occur during stop process leads to panic
which is false alarm. These errors do need panic because
controller is going to stop/start and invokes the
panel power off/power on. This patch removes the panic
from the cases where recovery handler is uninitialized.

Change-Id: I422d53d008223a9b0520f499e629f681bb6afa05
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>