bnxt_en: Add support to collect crash dump via ethtool

Driver supports 2 types of core dumps.

1. Live dump - Firmware dump when system is up and running.
2. Crash dump - Dump which is collected during firmware crash
                that can be retrieved after recovery.
Crash dump is currently supported only on specific 58800 chips
which can be retrieved using OP-TEE API only, as firmware cannot
access this region directly.

User needs to set the dump flag using following command before
initiating the dump collection:

    $ ethtool -W|--set-dump eth0 N

Where N is "0" for live dump and "1" for crash dump

Command to collect the dump after setting the flag:

    $ ethtool -w eth0 data Filename

v3: Modify set_dump to support even when CONFIG_TEE_BNXT_FW=n.
Also change log message to netdev_info().

Cc: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: Vasundhara Volam <vasundhara-v.volam@broadcom.com>
Signed-off-by: Sheetal Tigadoli <sheetal.tigadoli@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>