xapp_xinput-calibrator: rename directory to match .mk name

The directory was named xapp_xinput_calibrator, but the .mk file was
named xapp_xinput-calibrator.mk, which isn't consistent. Rename the
directory to xapp_xinput-calibrator to be consistent with the naming
of the .mk file and the other x11r7 directories.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>