i2c: scmi: Convert to be a platform driver

ACPI core in conjunction with platform driver core provides
an infrastructure to enumerate ACPI devices. Use it in order
to remove a lot of boilerplate code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Josef Johansson <josef@oderland.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>