phy: amlogic: Add Amlogic AXG MIPI/PCIE analog PHY Driver

This adds support for the MIPI analog PHY which is also used for PCIE
found in the Amlogic AXG SoC Family.

MIPI or PCIE selection is done by the #phy-cells, making the mode
static and exclusive.

For now only PCIE functionality is supported.

This PHY will be used to replace the mipi_enable clock gating logic
which was mistakenly added in the clock subsystem. This also activates
a non documented band gap bit in those registers that allows reliable
PCIE clock signal generation on AXG platforms.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Jerome Brunet <jbrunet@baylibre.com>