v4l2object: drop workaround for misbehaving TRY_FMT

v4l2object: drop workaround for misbehaving TRY_FMT

This workaround from 2011 was causing 25 S_FMT ioctls to be sent
to my UVC webcam from under gst_v4l2_object_get_caps as it probes
all the formats. In total, this adds up to about 5 seconds of
execution time, or a 10 second delay while starting up cheese.

These ioctls come from a workaround from 2011 where TRY_FMT might
make changes to hardware settings, so S_FMT was used to restore
the original config:
https://bugzilla.gnome.org/show_bug.cgi?id=649067

The driver bug is now assumed fixed. Remove the workaround to fix the
long startup delay.

https://bugzilla.gnome.org/show_bug.cgi?id=732326