PCI: mt7621: Add missing MODULE_LICENSE()

The MT7621 PCIe host controller driver can be built as a module, but it
lacks a MODULE_LICENSE(), which causes a build error:

  ERROR: modpost: missing MODULE_LICENSE() in drivers/pci/controller/pcie-mt7621.o

Add MODULE_LICENSE() to the driver.

Fixes: 2bdd523 ("PCI: mt7621: Add MediaTek MT7621 PCIe host controller driver")
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Yanteng Si <[email protected]>
Signed-off-by: Sergio Paracuellos <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Reviewed-by: Krzysztof Wilczyński <[email protected]>

Author: paraka

drivers/pci/controller/pcie-mt7621.c

@@ -561,3 +561,5 @@ static struct platform_driver mt7621_pci_driver = {
 	},
 };
 builtin_platform_driver(mt7621_pci_driver);
+
+MODULE_LICENSE("GPL v2");