IMS-VT: Speaker icon is not highlighted sometimes for MO VT calls.

If speaker icon is checked before the background color is updated,
it displays as unchecked after background update. This causes
speaker to appear as not enabled in some MO VT call cases even
though actual speaker functionality is enabled.
To fix this, uncheck the button before applying background color
and re apply the saved checked state after background is updated.

Change-Id: I67a95c5b217941eb5c18a993f672d8f577a29e3a
CRs-Fixed: 1008869