remoteproc: add INTMEM resource type for migration compatibility

A new resource type RSC_INTMEM has been added to the list of
resource types just to provide migration compatibility instead
of outright failures on loading of firmwares built against prior
kernels that have implemented this resource type properly. This
resource type was used to support loading of certain firmware
sections into processor internal memories (eg: RAM at L1 or L2
levels), but the solution has been rejected upstream. The added
handler function prints a warning advising the firmwares to move
away from using this resource type.

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