ice: fix PCI device serial number to be lowercase values

Commit ceb2f007 ("ice: Use pci_get_dsn()") changed the code to
use a new function to get the Device Serial Number. It also changed
the case of the filename for loading a package on a specific NIC
from lowercase to uppercase. Change the filename back to
lowercase since that is what we specified.

Fixes: ceb2f007 ("ice: Use pci_get_dsn()")
Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ice/ice_main.c

@@ -3248,7 +3248,7 @@ static char *ice_get_opt_fw_name(struct ice_pf *pf)
 	if (!opt_fw_filename)
 		return NULL;
 
-	snprintf(opt_fw_filename, NAME_MAX, "%sice-%016llX.pkg",
+	snprintf(opt_fw_filename, NAME_MAX, "%sice-%016llx.pkg",
 		 ICE_DDP_PKG_PATH, dsn);
 
 	return opt_fw_filename;