iwlwifi: mvm: support fw reading empty OTP

If the OTP is empty, the NVM_GET_INFO command returns
with flags' bit(0) on. This means the FW returns the
default values for working with. This is allowed, so
use this returned data.

Fixes: e9e1ba3d ("iwlwifi: mvm: support getting nvm data from firmware")
Signed-off-by: Liad Kaufman <liad.kaufman@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>