broadcom/vc4: Bump libdrm requirement

Require a version of libdrm with syncobj support.

v2: Don't require a libdrm_vc4, just bump core libdrm if vc4 enabled (by
    anholt)

Signed-off-by: Stefan Schake <stschake@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
diff --git a/meson.build b/meson.build
index b8ebda9..0f88ddf 100644
--- a/meson.build
+++ b/meson.build
@@ -1055,6 +1055,12 @@
   ['freedreno', with_gallium_freedreno],
 ]
 
+# VC4 only needs core libdrm support of this version, not a libdrm_vc4
+# library.
+if with_gallium_vc4
+  _drm_ver = '2.4.89'
+endif
+
 # Loop over the enables versions and get the highest libdrm requirement for all
 # active drivers.
 foreach d : _libdrm_checks