ARM: 5754/1: ep93xx: update i2c support

Update the ep93xx i2c support:

  1) The platform init code passes the configuration data for the
     i2c-gpio driver.  This allows any gpio pin do be used for the
     sda and scl pins.  It also allows the platform to specify the
     udelay and timeout.
  2) Program the gpio configuration register to enable/disable the
     open drain drivers.  Note that this really only works if the
     sda and scl pins are set to EP93XX_GPIO_LINE_EEDAT and
     EP93XX_GPIO_LINE_EECLK.
  3) Update the edb93xx.c platform init to use the new support.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>