pinctrl: mvebu: add pin-muxing driver for the Marvell Armada 380/385

The Marvell Armada 380/385 are new ARM SoCs from Marvell, part of the
mvebu family, but using a Cortex-A9 CPU core. In terms of pin-muxing,
it is similar to Armada 370 and XP for the register layout, only
different in the number of available pins and their
functions. Therefore, we simply use the existing
drivers/pinctrl/mvebu/ infrastructure, with no other changes that the
list of pins and corresponding functions.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>