omap: overo: Configure mux for gpio10

This pad was previously configured for sysclkout_1.  This patch changes
the configuration to gpio_10 to reduce radiated noise from the 26Mhz
clock, as well as make the pin more generally useful.

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Acked-by: Philip Balister <philip@opensdr.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>