qtuio: fix build/link issue when Qt is built with debug support

Fixes http://autobuild.buildroot.net/results/6dcbf4ca3fcc5ec911ac7a1680f7cb381fd18fcb



qtuio appends _d to the library name when Qt was built with debug support,
breaking linking step for examples and staging/target install.

There's no real advantage to the _d suffix, so simply fix it by removing
the logic appending _d.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>