ASoC: wcd_cpe_services: Make sure CPE is inactive before access

CPE (codec processing engine) memory space is shared with CPE and
slimbus register access. Due to simiulatneous access, it is possible
that CPE can crash. Add fix to make sure that CPE is done accessing the
memory space before accessing the same through codec registers.

Change-Id: Idcc7c0620cf82bb0ca7ee9fb041d4c535287a275
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>