pinctrl: mvebu: armada-{370,375}: normalize PCIe pins

This commit normalizes the naming of PCIe pins to use 'rstout' instead
of 'rstoutn' or 'rst-out'.

Since only the subnames are changed, DT compatibility is not affected.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>