ARM: mvebu: prepare pm-board.c for the introduction of Armada 38x support

The pm-board.c code contains the board-specific logic to enter suspend
to RAM. Until now, the code supported only the Armada XP GP board, so
all functions and symbols were named with armada_xp_gp. However, it
turns out that the Armada 388 GP also uses the same 3 GPIOs protocol
to talk to the PIC microcontroller that controls the power supply.

Since we are going to re-use the same code with no change for Armada
38x, this commit renames the functions and symbols to use just
"armada" instead of "armada_xp_gp". Better names can be found if one
day other boards having a different protocol/mechanism are supported
in the kernel.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>