octeontx2-pf: Calculate LBK link instead of hardcoding

CGX links are followed by LBK links but number of
CGX and LBK links varies between platforms. Hence
get the number of links present in hardware from
AF and use it to calculate LBK link number.

Signed-off-by: Subbaraya Sundeep <sbhatta@marvell.com>
Signed-off-by: Sunil Goutham <sgoutham@marvell.com>
Signed-off-by: Rakesh Babu <rsaladi2@marvell.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>