ARM: PSCI: fix PSCI DT nodes generation failure

Currently, PSCI nodes are added after fdt has shrunk to its actual size.
Thus there may be not enough room to do so.
This patch move the nodes insertion to image_setup_libfdt,
where fdt still has much free space.
This patch rename the hook arch_fixup_memory_node to more generic
arch_fixup_fdt, to avoid adding another ARM specific hook to
arch neutral code, then make arch_fixup_fdt fixup memory node and insert
the PSCI DT nodes.

Signed-off-by: Ma Haijun <mahaijuns@gmail.com>
arm: sunxi: Compile DRAM related code only when building SPL

The code of DRAM initialization is only of interest when building the SPL. Move
it to the CONFIG_SPL-only list of files to build.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
arm: sunxi: Add basic A31 support

Add a new sun6i machine that doesn't do much for now.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
arm: sunxi: Setup the A31 UART0 muxing

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
ARM: sunxi: Add sun6i clock controller structure

The A31 has a new clock controller of its own. Add the structure representing
this controller register layout.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

Conflicts:
	arch/arm/include/asm/arch-sunxi/clock.h
ARM: sun6i: Setup the UART0 clocks

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>