ice: Fix macro name for IPv4 fragment flag

In IPv4 header, fragment flags indicate whether the packet needs
to be fragmented or not. The value 0x20 represents MF (More Fragment); fix
the macro name to match this.

Signed-off-by: Ting Xu <ting.xu@intel.com>
Signed-off-by: Jeff Guo <jia.guo@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>