gralloc4-vts: Correct plane layout test of RGBA_8888 and YCbCr_420

The patch enhanced the plane layout tests in verifyRGBA8888 and
Lock_YCRCB_420_SP with considerations of sample increment and
subsampling.

Test: VtsHalGraphicsMapperV4_0
Bug: 150461327
Change-Id: I16fce5f29ec927de110cbaf5767e0b585d3c1919
1 file changed