dmaengine: dw: Don't pollute CTL_LO on iDMA 32-bit

Intel iDMA 32-bit doesn't have a concept of bus masters and thus
there is no need to setup any kind of masters in the CTL_LO register.

Moreover, the burst size for memory-to-memory transfer is not what is says,
we need to have a corrected list of possible sizes. Note, that
the size of 8 items, each of that up to 4 bytes, is chosen because of
maximum of 1/2 FIFO, which is 64 bytes on Intel Merrifield.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>