hal: fix incorrect VOIP volume when device switch

During device switch, when voip playback mixer path
is updated for new backend , previously set volume
is not restored and default volume is applied. This
cause VOIP sound in maximum volume.

Fix this by setting cached volume level after device switch.

CRs-Fixed: 2166709
Change-Id: Id3d6fd4b80909db80104fc0109bf5d84c4858922