Update mHavePendingChanges when there are changes

Currently mHavePendingChanges is set manually from
updateDisplayConfigsLocked and updateColorModesLocked
but not from updateHdrCapabilitiesLocked, so if only
HDR capabilities change we dont invalidate mInfo.

This CL ensures mHavePendingChanges=true when
there were changes in updateDisplayProperties.

Bug: 159721029
Test: m services
Test: verify that b/159721029 doesn't reproduce
Change-Id: I387d983e0f8ca849d9ee2bfc7f0e721697f85336