egl: check the correct function pointer

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

Fixes: 991ec1b81a "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>

src/egl/drivers/dri2/egl_dri2.c

@@ -1455,6 +1455,8 @@ dri2_swap_interval(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSurface *surf,
                    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);
 }
 

src/egl/main/eglapi.c

@@ -1205,7 +1205,7 @@ eglSwapInterval(EGLDisplay dpy, EGLint interval)
                     surf->Config->MinSwapInterval,
                     surf->Config->MaxSwapInterval);
 
-   if (surf->SwapInterval != interval && drv->API.SwapInterval)
+   if (surf->SwapInterval != interval)
       ret = drv->API.SwapInterval(drv, disp, surf, interval);
    else
       ret = EGL_TRUE;