pinctrl: mvebu: Enable support for the Armada 37xx pinctrl driver

To enable support for the Armada 37xx pinctrl driver, we need to
change the Kconfig symbol for the Armada 7k/8k pinctrl driver and its
dependencies to distinguish between both platforms and drivers.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Konstantin Porotchkin <kostap@marvell.com>
Cc: Nadav Haklai <nadavh@marvell.com>