remoteproc: mediatek: Zero out only remaining bytes of IPI buffer

In scp_ipi_handler(), instead of zeroing out the entire shared
buffer, which may be as large as 600 bytes, overwrite it with the
received data, then zero out only the remaining bytes.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20240520112724.139945-1-angelogioacchino.delregno@collabora.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

Author: AngeloGioacchino Del Regno

drivers/remoteproc/mtk_scp.c

@@ -117,8 +117,8 @@ static void scp_ipi_handler(struct mtk_scp *scp)
 		return;
 	}
 
-	memset(scp->share_buf, 0, scp_sizes->ipi_share_buffer_size);
 	memcpy_fromio(scp->share_buf, &rcv_obj->share_buf, len);
+	memset(&scp->share_buf[len], 0, scp_sizes->ipi_share_buffer_size - len);
 	handler(scp->share_buf, len, ipi_desc[id].priv);
 	scp_ipi_unlock(scp, id);