msm: mhi_dev: Enable CMDB during restore mmio

During mhi_dev_restore_mmio() we call mhi_dev_mmio_mask_interrupts,
restore the backup registers and we enable only CTRL,CHDB interrupts.
This causes the CMDB do be in disabled state, so after first D3 cold
transition we don't get CMDB interrupt until it fires along with one of
the already enabled interrupts. This causes delay in processing CMDB
interrupts that host might have queued at a very early stage.
Change is to enable CMDB interrupts post mmio restore along with the
other interrupts.

Change-Id: I75acbeda3f6e7c50669be4db9190b8ccd5b1dd1e
Signed-off-by: Subramanian Ananthanarayanan <skananth@codeaurora.org>
Signed-off-by: Gauri Joshi <gaurjosh@codeaurora.org>