i40e: Report cmd->data in ETHTOOL_GRXCLSRLCNT instead of ETHTOOL_GRXCLSRULE

Based on review feedback from upstream cmd->data is not
defined in ETHTOOL_GRXCLSRULE but needs to be reported in
ETHTOOL_GRXCLSRLCNT. Also use a helper function to calculate the total
filter count.

Change-ID: Iaacbf729527b73290c4fdad837b379b44fd7dd20
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>