c2port: fix bogus Kconfig "default no"

Strictly speaking "no" is a valid, but undefined, Kconfig symbol. But what
obviously was meant here was "n".

While we're touching this Kconfig file also drop the superfluous
dependency on C2PORT for C2PORT_DURAMAR_2150. Its Kconfig entry is
already wrapped in "if C2PORT" and "endif".

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>