cxgb4: Don't attempt to upgrade T4 firmware when cxgb4 will end up as a slave

This patch adds a new common code routine to upgrade an adapter's
firmware.  This routine handles all of the complexities of working with the
the existing adapter firmware in order to quiesce the adapter and uP, etc.
For an automatic upgrade it will send a HELLO command to check if cxgb4
want/can upgrade firmware, i.e. if cxgb4 is MASTER and has newer firmware
that it wants to load and call the new common code routine t4_fw_upgrade.
Note that it should not issue a RESET command after a successful firmware
upgrade.

Signed-off-by: Jay Hernandez <jay@chelsio.com>
Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>