Apparently some versions of nolo don't mux the all the necessary GPMC
pins for the smc91x probe to work properly. Let's fix this issue
by adding mux support for GPMC to the kernel.

Note that GPMC clk needs input enabled for OnenNAND to work.

Cc: Kevin Hilman <khilman@kernel.org>
Cc: Roger Quadros <rogerq@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>