x86: tangier: Fix DMA controller IRQ polarity in CSRT

IRQ polarity in CSRT has the same definition as by ACPI specification
chapter 19.6.64 "Interrupt (Interrupt Resource Descriptor Macro)", i.e.
ActiveHigh is 0, and ActiveLow is 1. On Intel Tangier the DMA controller
IRQ polarity is ActiveHigh.

Note, in DSDT (see southcluster.asl) it's described correctly.

Fixes: 5e99fde3 ("x86: tangier: Populate CSRT for shared DMA controller")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>