omap: RX-51: Drop I2C-1 speed to 2200

The I2C-1 bus frequency on RX-51 should be 2.2 MHz. The speed is limited
by TWL5030/GAIA; a higher speed could lead to errors on the interface. The
maximum speed depends on the system clock for GAIA: 2.2 MHz (if 19.2 MHz),
2.4 MHz (26 MHz) or 2.9 MHz (38.4 MHz).

Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>