ASoC: msm: qdsp6v2: start voip configuration after prepare()

During consecutive voip calls, the cached configuration info
is used for the second and following calls. This is because
voip call is configured right after open() where all the
configuration parameters are not available yet. Fix by
starting the voip configuration only after prepare() call.

Change-Id: I358440b01b58c6322f0bc8c3f20f6d9e44eff783
Signed-off-by: Shiv Maliyappanahalli <smaliyap@codeaurora.org>