soc: qcom: enable QHEE kernel memory protection

Invoke a scm call immediately after self-modification of code region
due to arm errata to protect kernel's memory regions in stage 2 memory
mappings.

Change-Id: I4706ab50ca8f6fa558990564ff8dd4ff967add26
Acked-by: Dane Pitkin <dpitkin@codeaurora.org>
Signed-off-by: Zhen Kong <zkong@codeaurora.org>