Remove unused persist.demo.hdmirotationlock from display-product.mk

In pixel phone, we did not have the HDMI interface so we should remove
the persist.demo.hdmirotationlock from display-product.mk.

Bug: 144743205
Test: There is no failed selinux log regarding persist.demo.hdmirotationlock
Change-Id: I6663be6b7ee48078c5eae8c3941de66c87771a80
1 file changed