rpi64: Add support for raspberry pi 7 inches touchscreen

This work is part of the https://phabricator.apertis.org/T8450 task.

2 commits enable some kernel options for the touchscreen and pinctrl i2cmux The 3rd one adds patches to support the touchscreen:

• 0001..0009 are improvements to the attiny regulator driver from raspberrypi
• 0010 modifies the rpi device trees to split the i2c0 interface into i2c0 and i2c_csi_dsi with a pinctrl i2cmux
• 0011 Adds support for i2c polling on the input touchscreen driver (from raspberrypi)
• 0012 Adds raspberry pi 7 inch display support to the panel-simple driver
• 0013 Adds a device tree for the touchscreen (adapted from the raspberry pi overlays)