linux-postmarketos-allwinner: increase RCU stall timeouts (MR 5422)

This raises CONFIG_RCU_CPU_STALL_TIMEOUT from 21s to 60s and
CONFIG_RCU_EXP_CPU_STALL_TIMEOUT from 20ms to 60ms (the value `0` means
that it is set to the regular stall timeout divided by 1000).
The original values caused frequent kernel logs of
"rcu_preempt detected expedited stalls" while running CPU-intensive stuff
like waydroid and caused such processes or others like Phosh to crash.

The kernel defaults are 21 / 0 (21s / 21ms), though the config docs note that
the latter is "normally 20ms on Android devices". For what it's worth,
Debian 12's amd64 kernel uses the kernel defaults of 21 / 0 (21s / 21ms),
while OpenSUSE TW's amd64 kernel uses 60 / 0 (60s / 60ms) just like
this commit.

Ref: #2980