zink: unset rp_changed after initializing renderpass attachments

if fbfetch is setup here, it will flag rp_changed

this is already inside renderpass setup, however, so just unset it
to avoid erroneously trigering the assert

cc: mesa-stable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19065>

src/gallium/drivers/zink/zink_render_pass.c

@@ -628,6 +628,8 @@ begin_render_pass(struct zink_context *ctx)
    infos.pAttachments = att;
    if (!prep_fb_attachments(ctx, att))
       return 0;
+   /* this can be set if fbfetch is activated */
+   ctx->rp_changed = false;
 #ifndef NDEBUG
    const unsigned cresolve_offset = ctx->fb_state.nr_cbufs + !!ctx->fb_state.zsbuf;
    for (int i = 0; i < ctx->fb_state.nr_cbufs; i++) {