fix "undefined method `split' for true:TrueClass" with grub2-efi

Fix error that pops up when using yast2 bootloader in GRUB2-EFI mode.
Selecting 'Boot Loader Options' and adjusting the options results in the above
error and the changes are lost.  (bnc#855568)
Merge pull request #33 from lpechacek/true_no_split

fix "undefined method `split' for true:TrueClass" with grub2-efi