stage1/init: remove "return 254" statements in favor of log.FatalE
stage1/init: remove "return 254" statements in favor of log.FatalE

Currently we have a lot of redundant "return 254" statements in
stage1/init. This removes them in favor of log.FatalE which internally
calls os.Exit(254).

coreos/rkt,joshix/rkt,intelsdi-x/rkt,kinvolk/rkt,rkt/rkt,cab105/rkt,jonboulle/rkt,Shashwatsh/rkt,kinvolk/rkt,Shashwatsh/rkt,rkt/rkt,ybubnov/rkt,Shashwatsh/rkt,alban/rkt,cab105/rkt,kinvolk/rkt,jonboulle/rkt,joshix/rkt,jakon89/rkt,ybubnov/rkt,jonboulle/rkt,sstabellini/rkt,achanda/rkt,dgonyeo/rkt,dgonyeo/rkt,kinvolk/rkt,rkt/rkt,shobhit85/rkt,jakon89/rkt,jakon89/rkt,dgonyeo/rkt,joshix/rkt,coreos/rkt,shobhit85/rkt,lucasallan/rkt,joshix/rkt,sstabellini/rkt,lucasallan/rkt,ybubnov/rkt,achanda/rkt,shobhit85/rkt,achanda/rkt,lucasallan/rkt,alban/rkt,alban/rkt,cab105/rkt,sstabellini/rkt,intelsdi-x/rkt,intelsdi-x/rkt,coreos/rkt,rkt/rkt,lucasallan/rkt