pinctrl: mvebu: armada-{38x,39x,xp}: normalize naming of DRAM functions

This commit makes the dram functions naming (both the name and
subname) consistent accross SoC, by using:

  dram(vttctrl)
  dram(deccerr)

in all Marvell SoCs.

Due to the change to the name, it changes the DT binding, but these
functions are not used by any in-tree Device Tree file, and are very
unlikely to be used by anyone.

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