msm_fb: display: Fix for HDMI bootup issue

If the device is booted up with HDMI cable connected, HDTV would go
blank unless the HDMI cable is removed and inserted again. This is
happening because the dtv pipe is initialized after HDMI core is
initialized. The dtv pipe needs to be allocated at the bootup time
when dtv is turned on to syncronize the HDMI core and DTV overlay.

CRs-fixed: 331867
Change-Id: I90f6434e8440548391a6846b47bb5539f2e436b7
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>