SoftAAC2: Modified conditions for format change notification

after decoding each frame.

Before: The format change notification would not be sent if
mInputBufferCount and mOutputBufferCount do not satisfy
(mInputBufferCount <= 2 || mOutputBufferCount > 1) even when sampleRate
and numChannels are valid and do not match the previous values.

Change: Check sampleRate and numChannels first. If they are valid and
do not match their previous values, the format change notification will
be sent regardless of the values of mInputBufferCount and
mOutputBufferCount. The OMX_EventError will still be sent under the same
condition.

Bug: 27645138
Change-Id: I5499b8495675744e04905c2d94c176fa1ada08e5