PCI: j721e: Add reset GPIO to struct j721e_pcie

Add reset GPIO to struct j721e_pcie, so it can be used at suspend and
resume stages.

Link: https://lore.kernel.org/linux-pci/20240102-j7200-pcie-s2r-v7-4-a2f9156da6c3@bootlin.com


Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>