Since hex_to_bin() is provided by hex.h there is no need to require
kernel.h. Replace the latter by the former and add missing export.h.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230604132858.6650-1-andriy.shevchenko@linux.intel.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>