ARM: ux500: Remove unnecessary attributes from DMA channel request pdata

DMA data width and packet size information is only required at channel
configuration time. Any information passed from platform data is passed
directly to the DMA40 driver to use during channel allocation, but these
pieces of information are subsequently ignored by the driver, so we may
as well remove them.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>