scsi: esas2r: constify pci_device_id.

pci_device_id are not supposed to change at runtime. All functions
working with pci_device_id provided by <linux/pci.h> work with const
pci_device_id. So mark the non-const structs as const.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Acked-by: Bradley Grove <bgrove@attotech.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>