Add the mlxfw module for Mellanox firmware flash process

The mlxfw module is in charge of common logic needed to flash Mellanox
devices firmware, which consists of:
 - Parse the Mellanox Firmware Archive version 2 (MFA2) format, which is
   the format used to store the Mellanox firmware. The MFA2 format file can
   hold firmware for many different silicon variants, differentiated by a
   unique ID called PSID. In addition, the MFA2 file data section is
   compressed using xz compression to save both file-system space and
   memory at extraction time.
 - Implement the firmware flash state machine logic, which is a common
   logic for Mellanox products needed to flash the firmware to the device.

As the module is shared between different Mellanox products, it defines a
set of callbacks to be implemented by the specific driver for hardware
interaction.

Signed-off-by: Yotam Gigi <yotamg@mellanox.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>