soc: qcom: scm: add check to avoid buffer overflow

There is a posibility of a buffer overflow in scm_call,
add check to avoid the same.

Change-Id: Iee908c56ec530569b35dafa060139e0428efc781
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>