soc: qcom: smem: Add boundary checks for partitions

Add condition check to make sure that the end address
of private entry does not go out of partition.

Change-Id: I88b3c69d86d90905b214c13a8c632b134b487a49
Signed-off-by: Sarannya S <quic_sarannya@quicinc.com>
Signed-off-by: Pranav Mahesh Phansalkar <quic_pphansal@quicinc.com>