wifi: iwlwifi: add a new FW file numbering scheme

wifi: iwlwifi: add a new FW file numbering scheme

Firmware releases follow a "Core N" pattern, but due to some
historical accidents, the API number for a Core N has always
been N+3. That's confusing for everyone.

For future firmware releases the firmware will make new file
names that, instead of being named with the API number, will
be named with the core number. For example, for the next one
for bz/fm it'd be "iwlwifi-bz-b0-fm-c0-c99.ucode" instead of
the now expected "iwlwifi-bz-b0-fm-c0-102.ucode".

In the driver, represent that as an offset of 1000, and then
request the "c<core>" format instead of just "<api>". When
looking for older versions, skip from 1099 to 101 (which is
core 98.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://patch.msgid.link/20250826184046.7bba17bf200b.I33044cf6d97c623c47f765ea467635f01fc88731@changeid