C2SoftVpxDec: Replace CHECK() with error handling

CHECK() for color format has been replaced with appropriate error
handling.

Bug: 117625412
Bug: 152070124
Test: stagefright -s -S /sdcard/cformat.webm
Test: stagefright -s -S /sdcard/crowd_640x360p50f32_frmPar_1x1.webm
Change-Id: I1fe0be54f9910fd98ff4db9240b4dcfd09888ffb
Merged-In: I1fe0be54f9910fd98ff4db9240b4dcfd09888ffb
1 file changed