msm: ADSPRPC: validate dma phy address after mapping

Validated buffer physical address to ensure contiguous and with in
ADSP heap memory area for remote processors without SMMU stage1.

Change-Id: Ia17fba6177ad9b2ebc8c7c38560d8f70025aaad9
Signed-off-by: Tharun Kumar Merugu <mtharu@codeaurora.org>