net: ethtool: get rid of get/set_rxfh_context functions

Add the RSS context parameters to struct ethtool_rxfh_param and use the
get/set_rxfh to handle the RSS contexts as well.

This is part 2/2 of the fix suggested in [1]:

 - Add a rss_context member to the argument struct and a capability
   like cap_link_lanes_supported to indicate whether driver supports
   rss contexts, then you can remove *et_rxfh_context functions,
   and instead call *et_rxfh() with a non-zero rss_context.

Link: https://lore.kernel.org/netdev/20231121152906.2dd5f487@kernel.org/ [1]
CC: Jesse Brandeburg <jesse.brandeburg@intel.com>
CC: Tony Nguyen <anthony.l.nguyen@intel.com>
CC: Marcin Wojtas <mw@semihalf.com>
CC: Russell King <linux@armlinux.org.uk>
CC: Sunil Goutham <sgoutham@marvell.com>
CC: Geetha sowjanya <gakula@marvell.com>
CC: Subbaraya Sundeep <sbhatta@marvell.com>
CC: hariprasad <hkelam@marvell.com>
CC: Saeed Mahameed <saeedm@nvidia.com>
CC: Leon Romanovsky <leon@kernel.org>
CC: Edward Cree <ecree.xilinx@gmail.com>
CC: Martin Habets <habetsm.xilinx@gmail.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Ahmed Zaki <ahmed.zaki@intel.com>
Link: https://lore.kernel.org/r/20231213003321.605376-3-ahmed.zaki@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>