modules: Kconfig: Provide default definitions for modules with blobs

There are HCI drivers which reference the module-specific Kconfig symbols
which are auto-generated when the modules are present. Provide default
definitions for these symbols in case the modules are missing, so that
compliance checking doesn't stumble over seemingly non-existent Kconfig
options.

Signed-off-by: Johan Hedberg <johan.hedberg@silabs.com>