ARM: dts: sun5i: Use most-qualified system control compatibles

This switches the sun5i dtsi to use the most qualified compatibles for
the system-control block (previously named SRAM controller) as well as
the SRAM blocks.

The node name for system control is also updated to reflect the fact that
the controller described is really about system control rather than SRAM
control.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
[Maxime: Removed the A10 compatible for the driver]
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>