MIPS: Malta: Probe pflash via DT

Add the DT nodes required to probe the CFI compatible parallel monitor
flash found on the Malta development board, and remove the platform
code that was previously doing it. Delete the now-empty malta-platform.c
file. Adjust the Malta defconfigs that enable MTD & the pflash/CFI
driver to enable CONFIG_MTD_PHYSMAP_OF rather than CONFIG_MTD_PHYSMAP in
order to preserve their behaviour.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14278/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>