Revert "i915: Move list_count() to list.h for broader use"

This reverts commit a9efc04c as it
breaks the build.

Link: https://lore.kernel.org/r/20221130131854.35b58b16@canb.auug.org.au
Link: https://lore.kernel.org/r/202211301628.iwMjPVMp-lkp@intel.com


Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>