driver: soc: apr: Clean up files and codes related to SMD

APR files and codes based on SMD are no longer needed for
future targets. Clean up them from kernel 4.9 codebase.

CRs-Fixed: 2006836
Change-Id: I03bc1088dd54d900974c2ed5ce59a1c419ff95b8
Signed-off-by: Xiaoyu Ye <benyxy@codeaurora.org>