rockchip: ringneck-px30/puma-rk3399: factor out storage medium selection

Ringneck PX30 and Puma RK3399 both have the same expectation with regard
to bootstd device order and U-Boot environment storage device, except
that Puma RK3399 also supports SPI Flash.

Let's move all of this into a common file where common logic can be put.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

rockchip: add support for PX30 Ringneck SoM on Haikou Devkit

The PX30-µQ7 (Ringneck) is a system-on-module featuring the Rockchip
PX30 in a micro Qseven-compatible form-factor.

PX30-µQ7 features:
* CPU: quad-core Cortex-A35
* DRAM: 2GB dual-channel
* eMMC: onboard eMMC
* SD/MMC
* TI DP83825I 10/100Mbps PHY
* USB:
* USB2.0 dual role port
* 3x USB2.0 host via onboard USB2.0 hub
* Display: MIPI-DSI
* Camera: MIPI-CSI
* onboard 2.4GHz WiFi + Bluetooth module
* Companion Controller: on-board additional microcontroller
(STM32 Cortex-M0 or ATtiny):
* RTC
* fan controller
* CAN (only STM32)

The non-U-Boot DTS files are imported from Linux v6.2-rc2.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>

rockchip: add support for PX30 Ringneck SoM on Haikou Devkit

The PX30-µQ7 (Ringneck) is a system-on-module featuring the Rockchip
PX30 in a micro Qseven-compatible form-factor.

PX30-µQ7 features:
* CPU: quad-core Cortex-A35
* DRAM: 2GB dual-channel
* eMMC: onboard eMMC
* SD/MMC
* TI DP83825I 10/100Mbps PHY
* USB:
* USB2.0 dual role port
* 3x USB2.0 host via onboard USB2.0 hub
* Display: MIPI-DSI
* Camera: MIPI-CSI
* onboard 2.4GHz WiFi + Bluetooth module
* Companion Controller: on-board additional microcontroller
(STM32 Cortex-M0 or ATtiny):
* RTC
* fan controller
* CAN (only STM32)

The non-U-Boot DTS files are imported from Linux v6.2-rc2.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>