ipu: Fix typos

Signed-off-by: Carlos Rafael Giani <dv@pseudoterminal.org>
pxp: Use ioctl's directly instead of imx-lib

imx-lib does not expose the cache flush call. Also, it always maps
allocated DMA buffers from the start, and not on-demand.

Signed-off-by: Carlos Rafael Giani <dv@pseudoterminal.org>