Revert "sunxi: remove a20 olinuxino lime2"

This reverts commit e361e93999318596208f7bd87fb07bfacd674f76.

cleaned up to current naming standard and enabled FEL mode

Conflicts:
	board/sunxi/Makefile
	boards.cfg
axp221: DCDC5 is 1.0 - 2.55V 50mV/step

This is shown in the min/max table in the datasheet and boot0 sources, the
actual register documentation in the datasheet is wrong.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>