Do not enable subsystem/driver shell modules by default and stop abusing
CONFIG_SHELL_MINIMAL, which is internal to the shell subsystem, to decide
when to enable a driver shell.
The list of shell modules has grown considerably through the
years. Enabling CONFIG_SHELL for doing e.g. an interactive debug session
leads to a large number of shell modules also being enabled unless
explicitly disabled, which again leads to non-negligible increases in
RAM/ROM usage.
This commit attempts to establish a policy of subsystem/driver shell
modules being disabled by default, requiring the user/application to
explicitly enable only those needed.
Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>