nouveau: Unify the style of function pointer calls in structs

Signed-off-by: Boyan Ding <boyan.j.ding@gmail.com>
diff --git a/src/mesa/drivers/dri/nouveau/nouveau_context.c b/src/mesa/drivers/dri/nouveau/nouveau_context.c
index cb854b8..6ddcadc 100644
--- a/src/mesa/drivers/dri/nouveau/nouveau_context.c
+++ b/src/mesa/drivers/dri/nouveau/nouveau_context.c
@@ -259,9 +259,9 @@
 	else if (fb->Visual.haveStencilBuffer)
 		attachments[i++] = __DRI_BUFFER_STENCIL;
 
-	buffers = (*screen->dri2.loader->getBuffers)(draw, &draw->w, &draw->h,
-						     attachments, i, &count,
-						     draw->loaderPrivate);
+	buffers = screen->dri2.loader->getBuffers(draw, &draw->w, &draw->h,
+						  attachments, i, &count,
+						  draw->loaderPrivate);
 	if (buffers == NULL)
 		return;