net/bnxt: add ULP flow counter manager

net/bnxt: add ULP flow counter manager

The Flow counter manager allocates memory to hold the software view
of the counters where the on-chip counter data will be accumulated
along with another memory block that will be shadowing the on-chip
counter data i.e where the raw counter data will be DMAed into from
the chip.
It also keeps track of the first HW counter ID as that will be needed
to retrieve the counter data in bulk using a TF API. It issues this cmd
in an rte_alarm thread that keeps running every second.

Signed-off-by: Somnath Kotur <somnath.kotur@broadcom.com>
Reviewed-by: Venkat Duvvuru <venkatkumar.duvvuru@broadcom.com>
Reviewed-by: Ajit Khaparde <ajit.khaparde@broadcom.com>