linux-phytec-fsl

drivers: base: dma-mapping: use nth_page helper

Use nth_page() helper instead of page_to_pfn() and pfn_to_page() to
simplify the code.

Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>