arm: da830: moved pinmux configurations to the arch tree

Move pinmux configurations for the DA830 SoCs from board file
to the arch tree so that it can be used for all da830 based devices.
Also, avoids duplicate pinmuxing in case of NAND.

Signed-off-by: Vishwanathrao Badarkhe, Manish <manishv.b@ti.com>
Reviewed-by: Tom Rini <trini@ti.com>
Acked-by: Christian Riesch <christian.riesch@omicron.at>