devkit-base: Add jitterentropy-rngd

This works around the RNG issue linux-emcraft#2 causing SSH logins to
be inaccessible for five minutes on boot.  With this package, SSH is
available immediately.
2 jobs for add-jitterentropy-rngd in 1 minute and 51 seconds (queued for 2 seconds)
latest
Status Name Job ID Coverage
  Build
passed build:deb #6755
librem5

00:01:26

passed build:docs #6754
librem5

00:01:51