ARM: OMAP4: Panda: rework DMM logic

ARM: OMAP4: Panda: rework DMM logic

Part of DMM logic is reuse from commit
47a4bea6af77b01d59a410d09a4c34b2dd14cf50 ("ARM: omap4: Update sdram
setting for panda rev A6") Which broke SDP4430 with ES2.3 (uses old
DDR).

So, to maintain support for newer DDR used in Panda ES rev B3, we
should, in addition to the commit
675cc77a3ae45e8b0ec17128563264d4a509f628 ("ARM:OMAP4+: panda-es: Support
Rev B3 Elpida DDR2 RAM"), DDR timings, also do DMM configuration
specific to Panda.

Signed-off-by: Nishanth Menon <nm@ti.com>