soc: qcom: Add cpaccess for AARCH64 targets.

cpaccess for AARCH64 targets lets users r/w to registers with access
permissions. cpaccess already exists for ARMv7. This is for AARCH64
ARMv8 mode.

Change-Id: I0122538fedd25a162956f45bf20a64e7db0ae03b
Acked-by: Suren Eda Naarayana Kulothungan <sedanaar@qti.qualcomm.com>
Signed-off-by: Neil Leeder <nleeder@codeaurora.org>