tests/kms_3d: Reduce the number of expected stereo 3D modes
tests/kms_3d: Reduce the number of expected stereo 3D modes

Currently the test expects to find 15 stereo 3D modes, however the
number of stereo modes we get from the current kernel EDID parser
is actually 13.

The extra two modes we had previously were GTF modes, which are no
longer getting added by the kernel since we have corresponding
CEA/DMT modes available. So having the GTF modes in the list was
not actually intentional.

The kernel commit that change the behaviour:
commit bfcd74d2aeda25a78f7cc92f80650218b1bce0ca
Author: Ville Syrjälä <cd6e8d405ca90be3a03d5427c5b24fbd2d68dcc4@linux.intel.com>
Date:   Thu Apr 2 17:02:11 2015 +0300

    drm/edid: Add DMT modes with ID > 0x50

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=90368
Signed-off-by: Ville Syrjälä <cd6e8d405ca90be3a03d5427c5b24fbd2d68dcc4@linux.intel.com>

dlespiau/checkmate-test-igt,dlespiau/checkmate-test-igt,mv0/intel-gpu-tools,chenxianqin/intel-gpu-tools,mv0/intel-gpu-tools,mv0/intel-gpu-tools,mv0/intel-gpu-tools,tiagovignatti/intel-gpu-tools,chenxianqin/intel-gpu-tools,tiagovignatti/intel-gpu-tools,tiagovignatti/intel-gpu-tools,dlespiau/checkmate-test-igt,chenxianqin/intel-gpu-tools,dlespiau/checkmate-test-igt,tiagovignatti/intel-gpu-tools,chenxianqin/intel-gpu-tools