msm: scm-pas: Provide a strongly ordered buffer to the secure world

The secure world requires that the metadata-containing buffer
be strongly ordered. Use the dma_alloc_attrs API to obtain a
strongly ordered region for this purpose.

Bug: 10750953
Change-Id: I98e3efb2ca34f897d50b624524d74b34e263ff84
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Mekala Natarajan <mekalan@codeaurora.org>