usb: xhci: use array_size() when allocating and freeing memory

Replace size_mul() with array_size() in memory allocation and freeing
processes, it fits better semantically.

Macro array_size() is identical to size_mult(), which clamps the max size,
so it's imperative that array_size() is used when freeing said memory.

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Niklas Neronin <niklas.neronin@linux.intel.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20240429140245.3955523-8-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>