acpi-dma: remove ugly conversion

In case of big endian CPU we have to convert either all fields in the structure
or leave this job to ACPICA. The second choice seems the best.

So, let's remove the ugly conversion that is not fully comprehensive anyway.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>