mmc: sdhci: increase the timeout value for data transfer

mmc: sdhci: increase the timeout value for data transfer

Timeout value is tunable.
When run read/write operation, sometime returned the timeout error.
Because the timeout value is too short.
So increased the enough timeout value.
(This timeout value is used to prevent the infinite loop.)

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>