ARM: dts: am335x-evm: add bluetooth support

uart1 is used for connecting to wilink8 bluetooth subsystem.
add the needed muxes and definitions.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Eyal Reizer <eyalr@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>