PCI: switchtec: Make switchtec_class constant

Now that the driver core allows for struct class to be in read-only memory,
we should make all 'class' structures declared at build time placing them
into read-only memory, instead of having to be dynamically allocated at
runtime.

Link: https://lore.kernel.org/r/2024061053-online-unwound-b173@gregkh


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-By: Logan Gunthorpe <logang@deltatee.com>
Cc: Kurt Schwemmer <kurt.schwemmer@microsemi.com>
Cc: Jon Mason <jdmason@kudzu.us>
Cc: Allen Hubbe <allenbh@gmail.com>