Revert "soc: qcom: Remove legacy scm_call API support"

This reverts commit bbb755a7.

Legacy smc_call support is needed for mdm9607,so adding
scm_call and scm_call_atomic related calls support.

Resolved conflits in scm.h and Makefile.

Change-Id: I03a2de9cd3ffb522f65ecd6dab90004bb3feb539
Signed-off-by: Haribabu Gattem <haribabu@codeaurora.org>
Signed-off-by: Sivasri Kumar Vanka <sivasri@codeaurora.org>