docs: kernel-parameters: Refer to the correct bitmap function

The parser of the CPU lists is bitmap_parselist() that supports
special notations with the plain numbers. bitmap_parse() never
supported those and will fail in case one will try it.

Fixes: b18def12 ("bitmap_parse: Support 'all' semantics")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230817140432.507889-1-andriy.shevchenko@linux.intel.com