dm: core: implement dev_map_physmem()

dm: core: implement dev_map_physmem()

This API helps to map physical register addresss pace of device to
virtual address space easily. Its just a wrapper around map_physmem()
with MAP_NOCACHE flag.

Signed-off-by: Vignesh R <[email protected]>
Suggested-by: Simon Glass <[email protected]>
Reviewed-by: Jagan Teki <[email protected]>
Reviewed-by: Simon Glass <[email protected]>
Signed-off-by: Jagan Teki <[email protected]>