ARM: dts: Update Nanobone dts file

Update dts file to reflect:-
* new flash memory layout
* add missing phy-mode property
* dual_emac now just a boolean
* rename mcp to microchip
* update gpio definition

Signed-off-by: Mark Jackson <mpfj@newflow.co.uk>
Signed-off-by: Tony Lindgren <tony@atomide.com>