iwlwifi: Start scratch debug register for Bz family

Start scratch debug register for Bz family.
This register is used for FW debug, and the driver
should start this register with a fixed value, during
init, and upon an error, should read it, and add it to
the dump.

Signed-off-by: Matti Gottlieb <matti.gottlieb@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210826224715.609ad58a49f3.I05c351233601ecc51dddfa5df69ace292216eb95@changeid


Signed-off-by: Luca Coelho <luciano.coelho@intel.com>