ARM: dts: sun5i: Fix the SRAM A3-A4 declaration

According to the system control bindings, the A3-A4 SRAM node should be
a child node of the SRAM it belongs to. However, it was introduced at the
same level, therefore breaking the binding. Fix this.

Fixes: 85870196 ("ARM: sun5i: a13: Merge common controllers into the common DTSI")
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>