mmc: mmc_spi: Convert to use for_each_sg()

Use for_each_sg() macro instead of open coded variant.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
1 file changed