MIPS: Malta: Setup RAM regions via DT

MIPS: Malta: Setup RAM regions via DT

Move memory configuration to be performed via device tree for the Malta
board. This moves more Malta specific code to malta-dtshim.c, leaving
the rest of the mti-malta code a little more board-agnostic. This will
be useful to share more code between boards, with the device tree
providing the board specifics as intended.

Since we can't rely upon Malta boards running a bootloader capable of
handling devictrees & filling in the required information, a piece of
shim code (malta_dt_shim) is added to consume the (e)memsize variables
provided as part of the bootloader environment (or on the kernel command
line) then generate the DT memory node using the provided values.

Signed-off-by: Paul Burton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: Kumar Gala <[email protected]>
Cc: [email protected]
Cc: Ian Campbell <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Pawel Moll <[email protected]>
Cc: Markos Chandras <[email protected]>
Cc: Mark Rutland <[email protected]>
Patchwork: https://patchwork.linux-mips.org/patch/11222/
Signed-off-by: Ralf Baechle <[email protected]>