msm_fb: hdmi: Fix for different resolution TV switch hang.

On connecting 1080p TV, then connecting 720p TV and then
connecting 1080p TV again results in system hang.
Hardware is waiting for reading AN in hdcp authentication part1
and then the resolution switch happens, which clears all the registers
and we are in lost state. We need to protect the reading of AN bits in
link status register and the reset core from muliple access.

CRs-fixed: 334143
Change-Id: Ic5399a79a37a4285b1d10998cb1ffb4913c39f51
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>