iwlwifi: mvm: support family 8000 C step

C step functionality in the driver is exactly the same as
B step besides the ucode name that present as iwlwifi-8000C-xx.ucode
instead of iwlwifi-8000B-xx.ucode

Signed-off-by: Eran Harary <eran.harary@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>