msm: pil: Make PIL shutdown ops optional
msm: pil: Make PIL shutdown ops optional

pil_shutdown() should be callable by pil drivers to de-assert proxy
votes, even if the pil driver doesn't implement shutdown ops.

Change-Id: I6a4468b07276d068765e13d41270d41f4bf5c570
Signed-off-by: Matt Wagantall <f353a1326f7aad71d23381a3beb9470c3b31d81b@codeaurora.org>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas