PCI: tegra: Constify static structs

PCI: tegra: Constify static structs

The only usage of them is to assign their address to the 'ops' field in
the pcie_port and the dw_pcie_ep structs, both which are pointers to
const. Make them const to allow the compiler to put them in read-only
memory.

Link: https://lore.kernel.org/r/20210207221604.48910-1-rikard.falkeborn@gmail.com
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>