PCI: j721e: Fix module autoloading

Commit a2790bf8 ("PCI: j721e: Add support to build as a loadable
module") added support to build the driver as a loadable module. However,
it did not add MODULE_DEVICE_TABLE() which is required for autoloading the
driver based on device table when it is built as a loadable module.

Fix it by adding MODULE_DEVICE_TABLE.

Fixes: a2790bf8 ("PCI: j721e: Add support to build as a loadable module")
Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
[mani: reworded description]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250901120359.3410774-1-s-vadapalli@ti.com