arm64: dts: rockchip: Add accelerometer sensor to Pinephone Pro

arm64: dts: rockchip: Add accelerometer sensor to Pinephone Pro

Pinephone Pro uses mpu6500 according to the schematic. This was verified
via `monitor-sensor --accel`. While rotating the device, the output was
correct (eg. when it was face up, left edge was up, vertical, etc.).

Co-developed-by: Martijn Braam <martijn@brixit.nl>
Signed-off-by: Martijn Braam <martijn@brixit.nl>
Co-developed-by: Kamil Trzciński <ayufan@ayufan.eu>
Signed-off-by: Kamil Trzciński <ayufan@ayufan.eu>
Signed-off-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
Reviewed-by: Pavel Machek <pavel@ucw.cz>
Link: https://patch.msgid.link/20251124-ppp_light_accel_mag_vol-down-v5-2-f9a10a0a50eb@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>