configs/minnowboard_max-graphical_defconfig: unbreak X11/mesa

Fixes https://gitlab.com/buildroot.org/buildroot/-/jobs/1297337965



Commit 15a2f9b8 (package/{mesa3d, mesa3d-headers}: bump
version to 21.0.2) marked BR2_PACKAGE_MESA3D_DRI_DRIVER_SWRAST as legacy,
but forgot to update the defconfig.  The SW rasterizer isn't really needed
with the Intel GPU, so just drop it.

In addition, X11 now needs some help with loading the modules in the correct
order, similar to how it was done for the test in commit 4a3639ba
(support/testing: test_glxinfo load X11 modules in the right order).

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>