iwlwifi: read and parse PNVM file

The driver looks for a PNVM file that contains FW configuration data
for each different HW combination.  The FW requests the data for a
certain SKU_ID and the driver tries to find it in the PNVM file.

Read the file, parse its contents and send it to the trans.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20201008181047.826bc607e57a.I1d93dd6e6651586878db57fac3e7c3f09d742c42@changeid