bnx2x: use napi_schedule_irqoff()

bnx2x_msix_fp_int() and bnx2x_interrupt() run from hard interrupt
context.

They can use napi_schedule_irqoff() instead of napi_schedule()

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Ariel Elior <ariel.elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>