soc: qcom: secure_buffer: Migrate to qcom_scm usage

Use qcom_scm_assign_mem_regions() when switching
ownership of several memory regions.

Change-Id: If6337af580e9e0cf4b484f81bd2870a02292cdba
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>