Generalize iwl_pnvm_parse(). This saves us from copying each payload
twice (first in the parsing and later when copying it to the dram).
Moreover, its  more compatible for handling larger pnvm tables in
the future (in which payloads won't be concatenated).

The main changes are:

1. Take out the concatenating of the payloads from the parsing level
2. Start using iwl_pnvm_image structure that will hold pointers to
payloads that should be delivered to fw, their sizes and number.
Signed-off-by: Alon Giladi <alon.giladi@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230606103519.06c02f380b6f.I03a3030fca194aa0c4bc2ecd18531f8914e98cfd@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>