xinput-calibrator: Fix service file to require display-manager.service

xinput-calibrator: Fix service file to require display-manager.service

The xinput-calibrator.service had a requires to xserver-nodm.service
but in fact it ought to wait by any display-manager to be initialized.
We fix it changing the require to display-manager.service.

(From meta-openembedded rev: ade2d4d35e1efdd83bb555949bcfb8c7a1970ff0)

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Patrick Ohly <patrick.ohly@intel.com>