Sparse complains about mt7621_pci_ops symbol is not declared and asks if
it should be declared as static instead. Sparse is right. Hence declare
symbol as static.

Link: https://lore.kernel.org/r/20211117152952.12271-1-sergio.paracuellos@gmail.comReported-by: Nkernel test robot <lkp@intel.com>
Signed-off-by: NSergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>
Reviewed-by: NKrzysztof Wilczyński <kw@linux.com>