ARM: sun8i: smp: Add support for A83T

Add the support for A83T.

A83T SoC has an additional register than A80 to handle CPU configurations:
R_CPUS_CFG. Information about the register comes from Allwinner's BSP
driver.
An important difference is the Power Off Gating register for clusters
which is BIT(4) in case of SUN9I-A80 and BIT(0) in case of SUN8I-A83T.
There is also a bit swap between sun8i-a83t and sun9i-a80 that must be
handled.

Signed-off-by: Mylène Josserand <mylene.josserand@bootlin.com>
Acked-by: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>