travis-ci: enable root checks
Revert "tests: ts_scsi_debug_init must not run in a subshell"

This reverts commit e92a928effd142c42b2960f34a73563fee025b84.
tests: cleanup ts_scsi_debug_init
tests: ts_scsi_debug_init must not run in a subshell

ts_skip and ts_die won't work from subshell. Now we simply use
DEVNAME which were still globally set in that function.
travis, debug losetup