sh_mobile_meram: MERAM framework for LCDC

Based on the patch by Takanari Hayama <taki@igel.co.jp>

Adds support framework necessary to use Media RAM (MERAM)
caching functionality with the LCDC.  The MERAM is accessed
through up to 4 Interconnect Buffers (ICBs).

ICB numbers and MERAM address ranges to use are specified in
by filling in the .meram_cfg member of the LCDC platform data

Signed-off-by: Damian Hobson-Garcia <dhobsong@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>