qed: Add abstraction for different hsi values per chip

The number of BTB blocks was modified to be different between the two chip
flavors supported (BB/K2) as a result, this lead to a re-write of selecting
the default hsi value based on the chip.
This patch creates a lookup table for hsi values per chip rather than
ask again and again for every value.

Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>