ASoC: msm8998: Add check before dereferencing pointer

Add check for pinctrl structure pointer before
dereferencing to avoid invalid memory access.

CRs-fixed: 1116515
Change-Id: I91e08278270ba24b6776975a651b75e0d83dc3d0
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>