Some recoverymap fixes from initial Ittiam feedback.

Add missing right shift to account for P010 data format. This is
because the 6 LSBs are ignored for each 16-bit data element.

Also fix potential out-of-bounds indexing in sampleMap() by clamping
x/y_lower/upper values to the map size.

Bug: 252835416
Test: builds
Change-Id: I2064a507a458f1d5d20f3d48eca974a712307d4a