qcom: scm-pas: Remove legacy 8660 check

The MSM8660 is no longer supported. Remove the check in scm-pas
and the socinfo.h header include.

Change-Id: Id01e71b897880045375e4907b4c8edf25a880e99
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>