Backport sh-sci fixes to 6.12.y

Hi, stable team,

Please backport the following commits to 6.12.y:

1/ 239f11209e5f ("serial: sh-sci: Move runtime PM enable to sci_probe_single()") 2/ 5f1017069933 ("serial: sh-sci: Clean sci_ports[0] after at earlycon exit") 3/ 651dee03696e ("serial: sh-sci: Increment the runtime usage counter for the earlycon device")

These applies cleanly on top of 6.12.y (if applied in the order provided above) and fix the debug console on Renesas devices.

Thank you, Claudiu Beznea