bnxt_en: Fix rx_l4_csum_errors counter on 57500 devices.

bnxt_en: Fix rx_l4_csum_errors counter on 57500 devices.

The software counter structure is defined in both the CP ring's structure
and the NQ ring's structure on the new devices.  The legacy code adds the
counter to the CP ring's structure and the counter won't get displayed
since the ethtool code is looking at the NQ ring's structure.

Since all other counters are contained in the NQ ring's structure, it
makes more sense to count rx_l4_csum_errors in the NQ.

Fixes: 50e3ab7836b5 ("bnxt_en: Allocate completion ring structures for 57500 series chips.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>