remoteproc/omap: add the rproc ops .da_to_va() implementation

An implementation for the rproc ops .da_to_va() has been added
that provides the address translation between device addresses
to kernel virtual addresses for internal RAMs present on that
particular remote processor device. The implementation provides
the translations based on the addresses parsed and stored during
the probe.

This ops gets invoked by the exported rproc_da_to_va() function
and allows the remoteproc core's ELF loader to be able to load
program data directly into the internal memories.

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