ARM: dts: armada-xp: Replace deprecated spi-gpio properties

As stated in Documentation/devicetree/bindings/spi/spi-gpio.yaml,
'gpio-mosi' and 'gpio-sck' are deprecated properties.

Use the recommeded 'mosi-gpios' and 'sck-gpios' instead.

Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>