QtIFW

Fix Mkdir operation in uninstall

If Mkdir generates directories to target dir, then uninstall will fail to
remove those as targetDir is replaced with @RELOCATABLE_PATH@ when the
operations are written to dat file. Fixed so that @RELOCATABLE_PATH@ is
replaced with targetDir.

Task-number: QTIFW-1099
Change-Id: I52a0330a2645e2d4a5371ce0d6f1fb296878752f
Reviewed-by: Iikka Eklund <iikka.eklund@qt.io>