meson.build: KMS support also depends on dri2
Kernel modesettings support also depends on dri2, see ./hw/xfree86/drivers/modesetting/meson.build So update meson.build to reflect the changes made in configure.ac by commit 9c81b8f5 Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com> (cherry picked from commit 5d73a8b5)