dmaengine: dw: Distinguish ->remove() between DW and iDMA 32-bit

In the same way as done for ->probe(), call ->remove() based on
the type of the hardware.

While it works now due to equivalency of the two removal functions,
it might be changed in the future.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vkoul@kernel.org>