QNX: Allow app to run when spurious 2nd screen is reported

QNX: Allow app to run when spurious 2nd screen is reported

On the PlayBook, libscreen always seems to report the presence of a 2nd
display even when none is connected. This of course leads to the failure
to query this display for its physical size.

This patch relaxes the demand for a physical size to being for the
primary screen only.

Change-Id: If30b1fd704e7a194a426a0a9f0b85557478105f7
Reviewed-by: Andreas Holzammer <andreas.holzammer@kdab.com>
Reviewed-by: Frank Osterfeld <frank.osterfeld@kdab.com>
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>