pinctrl: mvebu: armada-{370,375,38x,39x}: normalize dev pins

This commit modifies the definition of the Device Bus interface pins
to be consistent accross SoCs. Especially, it removes the 'n'
indicators that we don't encode in the subnames of pins:

   'dev(wen0)' becomes 'dev(we0)'
   'dev(wen1)' becomes 'dev(we1)'
   'dev(oen)' becomes 'dev(oe)'
   etc.

In addition, it fixes the Armada 375 DT binding documentation, which
forgot to document the 'dev' function for MPP46, MPP57 and MPP63.

Since only the subnames are changed, this commit does not affect DT
compatibility.

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