mlxsw: spectrum: Validate firmware revision on init

Make the spectrum module check the current device firmware version, and if
it is below the supported version, use the libfirmware API to request a
firmware file with the supported firmware version and flash it to the
device using the mlxfw module.

The firmware file names are expected to be of Mellanox Firmware Archive
version 2 (MFA2) format and their name are expected to be in the following
pattern: "mlxsw_spectrum-<major>.<minor>.<sub-minor>.mfa2".

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