SoftXaac: Add OMX_AUDIO_AACObjectXHE to supported profiles list

OMX_AUDIO_AACObjectXHE enum was missing from supported profiles list
in SoftXaac plugin though it is supported

Bug: 112310991
Test: cts-tradefed run commandAndExit cts-dev --abi armeabi-v7a\
 -m CtsMediaTestCases -t android.media.cts.DecoderTestXheAac

Change-Id: I37d14662f89fb65f8196363a5c26bb63583d81b9