ARM: dts: imx23: introduce mmc0_sck_cfg

ARM: dts: imx23: introduce mmc0_sck_cfg

The Olimex Olinuxino board has a user led connected to SSP1_DETECT.
But since this pin is listed in mmc0_pins_fixup, it is already claimed
by MMC driver and this results in this error during boot:

[    1.390000] imx23-pinctrl 80018000.pinctrl: pin SSP1_DETECT already
  requested by 80010000.spi; cannot claim for leds
[    1.400000] imx23-pinctrl 80018000.pinctrl: pin-65 (leds) status -22
[    1.410000] imx23-pinctrl 80018000.pinctrl: could not request pin 65
   (SSP1_DETECT) from group led_gpio2_1.0  on device 80018000.pinctrl
[    1.420000] leds-gpio leds: Error applying setting, reverse things back
[    1.430000] leds-gpio: probe of leds failed with error -22

This fix it, introduce mmc0_sck_cfg and switch the Olinuxino board to it.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>