C2SoftMpeg2Dec: Remove invalid check for output buffer width

If outBuffer is specificed, displayStride is the stride of the
outBuffer (line 595). Then, the "Output buffer too small" check
ends up comparing a buffer's width to the buffer's own stride
which effectively requires that a buffer's width is equal to it's stride.

Bug: 155485791
Test: cts -t android.media.cts.DecoderTest
Change-Id: Ia66591f816aac0d8aad5c1b5b9a0aeff2cc80185