[Tizen] Add recognition of empty parameters in options of xwalk_backend

Empty path in -i option and incorrect pkgid in -r option were not
recognized. These parameters were unnecessary passed further to other
functions.

BUG=XWALK-3051
Merge pull request #2672 from doduda/XWALK-3051

[Tizen] Add recognition of empty parameters in options of xwalk_backend