x86: acpi: Enable ACPI companion for Intel iDMA 32-bit

ACPI has a capability to specify DMA parameters for DMA channel consumers.
To enable this for Intel Edison, describe GP DMA device in ACPI table
in order to get an ACPI handle to it in OS.

This works in conjunction with CSRT, which must be in align with DSDT.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>