serial: sc16is7xx: Drop of_match_ptr() use

There is an ACPI method to enumerate such devices via specific ACPI ID
and use of compatible strings. It will not work for the drivers which
have no OF match ID table present.

Reported-by: Georgii Staroselskii <georgii.staroselskii@emlid.com>
Tested-By: Georgii Staroselskii <georgii.staroselskii@emlid.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>