iwlwifi: Add support for getting rf id with blank otp

When having a blank OTP the only way to get the rf id
and the cdb info is from prph registers.

Currently there is some implementation for this, but it
is located in the wrong place in the code (should be before
trying to understand what HW is connected and not after),
and it has a partial implementation.

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.20210826224715.820c2ae18c2b.Iec9b2e2615ce65e6aff5ce896589227a7030f4cf@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>