VA_FGLRXGetClientDriverName() used to return success even if no
valid driver name was found, thus returning a NULL driver name.

Also fixed the X display name matching routine to filter out the
screen number, which may not be in the string, and make sure to
compare screen numbers from what ADL returns too.
Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>