iwlwifi: mvm: support dumping UMAC internal txfifos

In case of FW error, support dumping the UMAC internal txfifos.
To do so, support version 2 of shared memory cfg command, which
contains the sizes of the internal txfifos, and move the command
to the system group.

Signed-off-by: Golan Ben-Ami <golan.ben.ami@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>