bnxt_en: reject ETS settings that will starve a TC

ETS proportions are presented to HWRM_QUEUE_COS2BW_CFG as minimum
bandwidth constraints. Thus, zero is a legal value for a given TC.
However, if all the other TCs sum up to 100%, then at least one
hardware queue will starve, resulting in guaranteed TX timeouts.
Reject such nonsensical configurations.

Reviewed-by: Pavan Chebbi <pavan.chebbi@broadcom.com>
Signed-off-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>