boards: mimxrt1060_evk: Add Arduino SPI support

When ever a Ardunio UNO R3 compatible shield will be used
together with the NXP MIMXRT1060-EVK board Zephyr runs into
an DTS parse error because of missing label 'arduino_spi'.

On NXP MIMXRT1060-EVK pin D10 (CS), D11 (MOSI), D12 (MISO)
and D13 (CLK) are disconnected in default and can be closed
optionally. But keep in mind that the signals are already
connected to a on-board component: TF/SD-Card in default
or M.2(E) header for an optional WiFi module.

Signed-off-by: Stephan Linz <linz@li-pro.net>