ARM: sun6i: dt: Fixup prcm node name

The prcm lives at address 0x01f01400 as the reg entry in its node already
correctly indicates, rename the node to match this.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>