MIPS: mobileye: eyeq5: add OLB system-controller node

The OLB ("Other Logic Block") is a system-controller region hosting
clock, reset and pin controllers. It contains registers such as I2C
speed mode that need to be accessible by other nodes.

Remove fixed-clocks previously used; replace references.
Add parent crystal clock, fixed at 30MHz.
Add pin nodes for all functions.
Add mobileye,eyeq5-olb compatible node, hosting clk, reset and pinctrl.
Add reset and pinctrl references to UART nodes.

Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>