parport: Drop even more unneeded NULL or 0 assignments

kzalloc() gives us a zeroed memory, no need to explicitly assing 0 or
NULL or similar to the members of the data structure that has been
allocated with the above mentioned API.

Note, the initializstion of full_list member is not needed anymore
as list_add_tail will rewrite the contents of the prev and next
pointers.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20231018145948.1367648-2-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>