bnxt_en: Fix statistics context reservation logic.

In an earlier commit that fixes the number of stats contexts to
reserve for the RDMA driver, we added a function parameter to pass in
the number of stats contexts to all the relevant functions.  The passed
in parameter should have been used to set the enables field of the
firmware message.

Fixes: 780baad4 ("bnxt_en: Reserve 1 stat_ctx for RDMA driver.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>