The MPP52 signal is on the seconds GPIO instance of CP0, which
corresponds to the &cp0_gpio2 handle.

Rename the property name to the standard '-gpios' suffix while at it.

Fixes: b83e1669 ("arm64: dts: marvell: mcbin: add support for PCIe")
Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>