In Baytrail and Quark support code acpi_fill_madt() is identical.

Deduplicate its implementation by moving to lib/acpi_tables.c.

At the same time mark acpi_fill_madt() with __weak attribute to keep a
possibility to override it in platform code
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: NBin Meng <bmeng.cn@gmail.com>