edb93xx SDRAM initialization: Issue a precharge all command before forcing the
precharge of all SDRAM banks. Write to the SDRAM in order to force a precharge,
reading causes the edb93xx boards to hang
Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>