ARM: dts: tacoma: Hog LPC pinmux

Requesting pinmux configuration is done at driver probe time. The LPC IP
is composed of many sub-devices, each with their own driver, and no
driver exists for the entire IP block. Avoid having each sub-device
request the LPC pinmux by just hogging it in the pinctrl node.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Joel Stanley <joel@jms.id.au>