camera2: Reduced Ultra high resolution sensors.

Add documentation stating that it is possible for camera devices
not supporting the ULTRA_HIGH_RESOLUTION_SENSOR capability to still
switch sensor pixel modes. Also add documentation to the related
*MAXIMUM_RESOLUTION tags mentioning they can be present when the
ULTRA_HIGH_RESOLUTION_SENSOR capability is not present. They may
also be present when SENSOR_PIXEL_MODE is listed in the available
capture request keys.

Bug: 261232769

Test: build

Change-Id: I0c35ad8e435b68cdfc1d70da8a2e5a96c35e10ba
Signed-off-by: Jayant Chowdhary <jchowdhary@google.com>