remoteproc/pruss: add support to parse IEP & MII_RT resources

Add support to parse and store the IEP and MII_RT module memory
resources to the PRUSS platform driver. These memory resources
are now mandatory on every PRUSS node.

Users would need to access these resources and they must request
and release them using pruss_request_mem_region() and
pruss_release_mem_region() API.

Signed-off-by: Roger Quadros <rogerq@ti.com>
[s-anna@ti.com: use proper name MII_RT, revise commit description]
Signed-off-by: Suman Anna <s-anna@ti.com>