octeontx2-af: CGX: add bounds check to cgx_speed_mbps index

octeontx2-af: CGX: add bounds check to cgx_speed_mbps index

cgx_speed_mbps has 13 elements but RESP_LINKSTAT_SPEED can yield values
0-15. If it returns a value >= 13, this causes an out-of-bounds array
access. Add a bounds check and default to speed 0 if the index is out of
range.

Fixes: 61071a871ea6 ("octeontx2-af: Forward CGX link notifications to PFs")
Cc: Sunil Goutham <sgoutham@marvell.com>
Cc: Linu Cherian <lcherian@marvell.com>
Cc: Geetha sowjanya <gakula@marvell.com>
Cc: hariprasad <hkelam@marvell.com>
Cc: Subbaraya Sundeep <sbhatta@marvell.com>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Cc: stable <stable@kernel.org>
Signed-off-by: Sam Daly <sam@samdaly.ie>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://patch.msgid.link/2026051352-refined-demise-e88d@gregkh
Signed-off-by: Jakub Kicinski <kuba@kernel.org>