tty: serial: sc16is7xx: convert to use maple tree register cache

The maple tree register cache is based on a much more modern data structure
than the rbtree cache and makes optimisation choices which are probably
more appropriate for modern systems than those made by the rbtree cache.

Signed-off-by: wangkaiyuan <wangkaiyuan@inspur.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240318064216.1765-1-wangkaiyuan@inspur.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>