sfc: fix deadlock in RSS config read

sfc: fix deadlock in RSS config read

Since cited commit, core locks the net_device's rss_lock when handling
 ethtool -x command, so driver's implementation should not lock it
 again.  Remove the latter.

Fixes: 040cef30b5e6 ("net: ethtool: move get_rxfh callback under the rss_lock")
Reported-by: Damir Mansurov <damir.mansurov@oktetlabs.ru>
Closes: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1126015
Suggested-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://patch.msgid.link/20260123161634.1215006-1-edward.cree@amd.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>