drm/panel: nt35510: support FRIDA FRD400B25025-A-CTK

The initialization commands are taken from the STMicroelectronics driver
found at [1].
To ensure backward compatibility, flags have been added to enable gamma
correction setting and display control. In other cases, registers have
been set to their default values according to the specifications found
in the datasheet.

[1] https://github.com/STMicroelectronics/STM32CubeF7/blob/master/Drivers/BSP/Components/nt35510/

Signed-off-by: Dario Binacchi <[email protected]>
Signed-off-by: Linus Walleij <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]