Remove unused #address-cells and #size-cells from pinmux
node. This fixes W=1 warnings of the type:

arch/arm/boot/dts/da850-lcdk.dtb: Warning (avoid_unnecessary_addr_size): /soc@1c00000/pinmux@14120: unnecessary #address-cells/#size-cells without "ranges" or child "reg" property

Tested on DA850 LCDK by checking output of:

/sys/kernel/debug/pinctrl/1c14120.pinmux-pinctrl-single/pins

before and after the change.
Reviewed-by: David Lechner <david@lechnology.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>