arm64: dts: rockchip: add Rock 5B+

Add ROCK 5B+, which is an improved version of the ROCK 5B with the
following changes:

 * Memory LPDDR4X -> LPDDR5
 * HDMI input connector size
 * eMMC socket -> onboard
 * M.2 E-Key is replaced by onboard RTL8852BE WLAN/BT
 * M.2 M-Key 1x4 lanes is replaced by 2x2 lanes
 * Added M.2 B-Key for USB connected WWAN modules (untested)
 * Add second camera port (not yet supported in upstream Linux)
 * Add dedicated USB-C port for device power (no impact in DT;
   the existing port has not been changed and the new port is
   handled by CH224D standalone chip)

Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>