PCI/switchtec: Declare local state_names[] as static

The local state_names[] array is constant and need not be allocated and
populated each time we enter stuser_set_state().  Declare it as static.

See the link below for the discussion.

  https://lore.kernel.org/r/20211014141859.11444-1-kelvin.cao@microchip.com/



[bhelgaas: simplify commit log]
Suggested-by: Krzysztof Wilczyński <kw@linux.com>
Link: https://lore.kernel.org/r/20211119003803.2333-3-kelvin.cao@microchip.com


Signed-off-by: Kelvin Cao <kelvin.cao@microchip.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>