octeontx2-af: Fix default entries mcam entry action

As per design, AF should update the default MCAM action only when
mcam_index is -1. A bug in the previous patch caused default entries
to be changed even when the request was not for them.

Fixes: 570ba37898ec ("octeontx2-af: Update RSS algorithm index")
Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260216090338.1318976-1-hkelam@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>