tests/gem_flink_race,prime_self_import: fix object counts

tests/gem_flink_race,prime_self_import: fix object counts

We need to add one drm_open_any() before getting the object counts
as first call to drm_open_any() allocates file descriptors for
exit handlers and thus is not symmetrical.

The regression, assymmetric behaviour, was introduced in:

commit 2f2c491cf3167befe7c79e4b17afb4f6284dfc84
Author: Mika Kuoppala <mika.kuoppala@intel.com>
Date:   Fri Mar 28 10:52:46 2014 +0200

    lib/drmtest: don't dup quiescent fd

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77867
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77875
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>