egl: check the correct function pointer

`.swap_interval` != `.SwapInterval`...

Fixes: 991ec1b81a76de24fd01 "egl: make platform's SwapInterval() optional"
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=102015
Cc: Cedric Sodhi <manday@openmail.cc>
Signed-off-by: Eric Engestrom <eric.engestrom@imgtec.com>
Tested-by: Cedric Sodhi <manday@openmail.cc>
diff --git a/src/egl/drivers/dri2/egl_dri2.c b/src/egl/drivers/dri2/egl_dri2.c
index a197e04..733659d 100644
--- a/src/egl/drivers/dri2/egl_dri2.c
+++ b/src/egl/drivers/dri2/egl_dri2.c
@@ -1455,6 +1455,8 @@
                    EGLint interval)
 {
    struct dri2_egl_display *dri2_dpy = dri2_egl_display(dpy);
+   if (!dri2_dpy->vtbl->swap_interval)
+      return EGL_TRUE;
    return dri2_dpy->vtbl->swap_interval(drv, dpy, surf, interval);
 }