mmc: pxamci: remove the MMC_DATA_STREAM flag

Remove the MMC_DATA_STREAM flag because it isn't used anymore.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>