bnxt_en: Added support for Secure Firmware Update

Using Ethtool flashdev command, entire NVM package (*.pkg) files
may now be staged into the "update" area of the NVM and subsequently
verified and installed by the firmware using the newly introduced
command: NVM_INSTALL_UPDATE.

We also introduce use of the new firmware command FW_SET_TIME so that the
NVM-resident package installation log contains valid time-stamps.

Signed-off-by: Rob Swindell <Rob.Swindell@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>