Kconfig: Remove useless "default N" lines

A number of Kconfig entries default to (uppercase) "N". It was clearly
intended to use "default n". But since (lowercase) "n" is the default
anyway, these lines might as well be removed.

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