bnxt_en: Improve -ENOMEM logic in NAPI poll loop.

bnxt_en: Improve -ENOMEM logic in NAPI poll loop.

Orabug: 27648355, 27648339

If we cannot allocate RX buffers in the NAPI poll loop when processing
an RX event, the current code does not count that event towards the NAPI
budget.  This can cause us to potentially loop forever in NAPI if we
consistently cannot allocate new buffers.  Improve it by counting
-ENOMEM event as 1 towards the NAPI budget.

Cc: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Reported-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit 903649e718f80da2ba4b65a0adf6930219b4b2e5)
Signed-off-by: Brian Maly <brian.maly@oracle.com>
Reviewed-by: Jack Vogel <jack.vogel@oracle.com>