Always initialize "item"

Otherwise item.cfg_name and item.default_val
will contain garbage. It doesn't seem to have
an effect right now, but who knows what
a future refactoring might do.

cppcheck reported:
[rockbox/apps/settings.c:1268]: (error) Uninitialized variable: item

Change-Id: Ic4d0c302929613de8f291cd2d69cd39db8711107
Fix red (pass pointer of 'item')

Change-Id: I2d04251519623b2531948615c35e61203f9a9940
zxbox: Add missing break; statement

No harm done, same values are assigned
in the "default" case.

cppcheck reported:
[rockbox/apps/plugins/zxbox/tapefile.c:674] -> [rockbox/apps/plugins/zxbox/tapefile.c:681]: (warning) Buffer 'seg_desc' is being written before its old content has been used. 'break;' missing?

Change-Id: I2bf044db9022c848c304f1ad88c012bd85ee61df
mikmod plugin: Remove bogus doubled return statement
Stick to the safer version of those two.

Tested mikmod still works with some nice Necros .s3m files.

Change-Id: I6774cdf3345a4c89b2f9cf3bb8d832963ca30c38