sfc: remove get_rxfh_context dead code

The core now always satisfies 'ethtool -x context nonzero' from its own
 tracking, so our lookup code for that case is never called.  Remove it.

Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/b426fcc416dedc8f203e52eebef6891eccebe4c1.1719502240.git.ecree.xilinx@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>