ASoC: msm8x16-wcd: Fix slab corruption due to incorrect malloc size

In SSR, when reg_cache param is updated using kmemdup
size parameter used is reg_word_size which is value 1.
This will result in slab corruption. Update the size
parameter to correct size.

Change-Id: Ia4b30281f201bd4cef31d7068f021e7c964e0d30
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>