lib: packing: create __pack() and __unpack() variants without error checking

lib: packing: create __pack() and __unpack() variants without error checking

A future variant of the API, which works on arrays of packed_field
structures, will make most of these checks redundant. The idea will be
that we want to perform sanity checks at compile time, not once
for every function call.

Introduce new variants of pack() and unpack(), which elide the sanity
checks, assuming that the input was pre-sanitized.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/20241210-packing-pack-fields-and-ice-implementation-v10-1-ee56a47479ac@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>