ASoC: msm8x10-wcd: fix missing iounmap after ioremapped memory

If ioremap is used, iounmap has to be called. Missing iounmap call
cause flooding vmalloc table which will end up with random crashes.

CRs-fixed: 502923
Change-Id: I45fa48d583503470c8fa9549c9c5f60d903e38ed
Signed-off-by: Fred Oh <fred@codeaurora.org>