* modem-related modules seem partly responsible for recent l3 firewall
timeouts and kernel crashes.
* rx51-battery can be used to get battery design capacity, but not required
for general running of the system blacklist other
* modules that can impact power consumption on the N900
Completely disabling the modules in kernel config is unnecessary, since they
are all useful for some users
[ci:skip-build]: already built successfully in CI
Since N900 rtc works fine, remove swclock from boot as it causes time to be set
wrong. Additionally, rtc device is set correctly in kernel, so remove old,
adjusted hwclock config.
Partially reverts pmaports 0e502a5139
[ci:skip-build]: already built successfully in CI
