ASoC: msm: Check prepare state to avoid duplicate channel query

PCM prepare may be called for multiple times if any error occurs.
Check the prepare state in slim dai driver so that duplicate
slimbus channel query can be avoided.

CRs-Fixed: 1099101
Change-Id: I41ab0baf1bbe6ccda6b8da2ecd077bea2a388e56
Signed-off-by: Walter Yang <yandongy@codeaurora.org>
1 file changed