selftests: firmware: Add firmware upload selftests

Add selftests to verify the firmware upload mechanism. These test
include simple firmware uploads as well as upload cancellation and
error injection. The test creates three firmware devices and verifies
that they all work correctly and independently.

Tested-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Tianfei zhang <tianfei.zhang@intel.com>
Signed-off-by: Russ Weight <russell.h.weight@intel.com>
Link: https://lore.kernel.org/r/20220426163532.114961-1-russell.h.weight@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>