igc: Relocate RSS field definitions to igc_defines.h

igc: Relocate RSS field definitions to igc_defines.h

Move the RSS field definitions related to IPv4 and IPv6 UDP from igc.h to
igc_defines.h to consolidate the RSS field definitions in a single header
file, improving code organization and maintainability.

This refactoring does not alter the functionality of the driver but
enhances the logical grouping of related constants

Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Signed-off-by: Song Yoong Siang <yoong.siang.song@intel.com>
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Reviewed-by: Brett Creeley <brett.creeley@amd.com>
Tested-by: Mor Bar-Gabay <morx.bar.gabay@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>