edb93xx: Fix SDRAM initialization by issuing a precharge all command before
forcing the precharge and select mode register update mode before programming
the mode registers. Write to the SDRAM banks in order to force a precharge,
reading causes the edb93xx boards to hang
Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Added support for the following EDB93xx boards:
EDB9301
EDB9302
EDB9302A
EDB9307
EDB9307A
EDB93012
EDB9315
EDB9315A
Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>