fsl/fman: Add FMan MURAM support

Add Frame Manager Multi-User RAM support.
This internal FMan memory block is used by the
FMan hardware modules, the management being made
through the generic allocator.

The FMan Internal memory, for example, is used for
allocating transmit and receive FIFOs.

Signed-off-by: Igal Liberman <Igal.Liberman@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>