linux-*: drop python2 makedepend
3 kernels still had python2 in their makedepends. Drop it.
- linux-lenovo-p1m: the dependency was just wrong, builds fine without it
- linux-alcatel-5010d: include the generated cust.dtsi instead of running drvgen
- linux-wiko-lenny5: include the generated cust.dtsi instead of running drvgen
I've documented how to drop python2 dependencies from downstream kernels here: https://wiki.postmarketos.org/wiki/Porting_to_a_new_device#Removing_python2_dependency
This caused the CI of !3478 (merged) to fail.