In the case of two iso's ('xs-tools-6.0.2.iso' and 'xs-tools-6.0.2-1111.iso'),
TOOLS_ISO gets set to 'xs-tools-6.0.2-1111.iso xs-tools-6.0.2.iso' This causes
'mount -o loop xs-tools-6.0.2-1111.iso xs-tools-6.0.2.iso $TMP_DIR' to get
called, which fails as it's meant to be called with only one file. This fix
simply sets TOOLS_ISO to the first iso that ls returns.
Change-Id: Id4d883e2b1e33b233c9ee907016b4ce117c28021
98ab500c2c