hw/dma/omap_dma: Fix coding style in omap_dma_transfer_setup()

We're about to fix indent in a section of the
omap_dma_transfer_setup() function, which will make checkpatch
complain.  Since we're touching the code anyway, fix the uses of if()
with no braces and wrongly formatted multiline comments.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20260528152852.3349928-3-peter.maydell@linaro.org