bnxt_en: Fix wrong flag value passed to HWRM_PORT_QSTATS_EXT fw call.

The wrong flag value caused the firmware call to return actual port
counters instead of the counter masks.  This messed up the counter
overflow logic and caused erratic extended port counters to be
displayed under ethtool -S.

Fixes: 531d1d26 ("bnxt_en: Retrieve hardware masks for port counters.")
Reviewed-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>