phy: amlogic: phy-meson-axg-mipi-pcie-analog: add support for MIPI DSI analog

phy: amlogic: phy-meson-axg-mipi-pcie-analog: add support for MIPI DSI analog

The AXG Analog MIPI-DSI PHY also provides functions to the PCIe PHY,
thus we need to have inclusive support for both interfaces at runtime.

This fixes the regmap get from parent node, removes cell param
to select a mode and implement runtime configuration & power on/off
for both functions since they are not exclusive.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Remi Pommarel <repk@triplefau.lt>
Link: https://lore.kernel.org/r/20201116101647.73448-4-narmstrong@baylibre.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>