Fix initial buffer format for SoftVPX

Bug: 80553101

Test: playback VP9 profile 0 and profile 2 content with SoftVPX,
with verbose ACodec log, buffer shouldn't reallocate with profile0.
Check thumbnail generation in Photos work properly.

Change-Id: Ic488b110abee20b42f1877b23e763988dd8243b2
diff --git a/media/libstagefright/omx/SoftVideoDecoderOMXComponent.cpp b/media/libstagefright/omx/SoftVideoDecoderOMXComponent.cpp
index cd0f75c..935dc34 100644
--- a/media/libstagefright/omx/SoftVideoDecoderOMXComponent.cpp
+++ b/media/libstagefright/omx/SoftVideoDecoderOMXComponent.cpp
@@ -651,7 +651,6 @@
                 return OMX_ErrorBadPortIndex;
             }
 
-            mOutputFormat = OMX_COLOR_FormatYUV420Planar16;
             mHdrStaticInfo = hdrStaticInfoParams->sInfo;
             updatePortDefinitions(false);