wifi: iwlwifi: Take loading and setting of pnvm image out of parsing part

Change iwl_pnvm_parse so it will only save the information into the
iwl_pnvm_image struct. This enables to use the parsing code for the
power reduce tables in the future.

Signed-off-by: Alon Giladi <alon.giladi@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230606103519.504b42fc1611.I4ddf6ad76d922d118fcbcc4f0e9ec003753d0b75@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>