TEMP: remoteproc: add legacy support to handle internal memories

A remote processor may need to load certain firmware sections into
internal memories (eg: RAM at L1 or L2 levels) for performance or
other reasons. The deprecated function handler for the RSC_INTMEM
resource type has been modified to handle such memories. The handler
creates a kernel mapping for the resource's 'pa' (physical address).

Note that no iommu mapping is performed for this resource, as the
resource is primarily used to represent physical internal memories.
If the internal memory region can only be accessed through an iommu,
a devmem resource entry should be used instead.

WARNING NOTE:
This is a _temporary_ legacy solution from a prior kernel to handle
loading into internal memories. Firmwares are advised to move away
from using this resource type.

Signed-off-by: Robert Tivy <rtivy@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>