arm64: dts: rockchip: describe the OV8858 user camera on PinePhone Pro

arm64: dts: rockchip: describe the OV8858 user camera on PinePhone Pro

Add the description of the front/user camera (OV8858) on the PinePhone Pro
to the device dts file.
It receives commands over SCCB, an I2C-compatible protocol, at
I2C address 0x36 and transmits data over CSI-MIPI.
I confirmed this address experimentally.

The pin control mapping was again extracted from the PinePhone Pro
schematic v1.0 as well as the RK3399 datasheet revision 1.8.

Table 2-3 in section 2.8 of the RK3399 datasheet contains the mapping
of IO functions for the SoC pins. Page 52 shows GPIO1_A4, page 54 shows
GPIO2_B4.

For the reset (RESET) signal:
page 11 quadrant D2             | p.18 q.B3-4 | p.18 q.C2
RK3399_E.R28 -> GPIO1_A4 -> Camera2_RST -> MIPI_RST1 -> OV8858.12

For the powerdown (PWDN) signal:
page 9 quadrants D4-5          | p.18 q.B2
RK3399_L.F31 -> GPIO2_B4 -> DVP_PDN0_H -> OV8858.14

Helped-by: Dragan Simic <dsimic@manjaro.org>
Co-developed-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Ondrej Jirman <megi@xff.cz>
Signed-off-by: Olivier Benjamin <olivier.benjamin@bootlin.com>
Link: https://lore.kernel.org/r/20250620-camera-v4-4-0201a8ed5fae@bootlin.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>