[Tizen] Fix invalid path in crosswalk manifest for xwalk_backend binary

The path pointed to lib64 directory that does not exist in 32-bit platform.
So this patch adds another entry for 32-bit version of this binary.

BUG=XWALK-2806
Merge pull request #2544 from tweglarski/XWALK-2806

[Tizen] Fix invalid path in crosswalk manifest for xwalk_backend binary