mmc: tmio: use CTL_STATUS consistently

To prevent confusion, use the virtual u32 CTL_STATUS in card_busy() the
same way as in other parts of this driver.

Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>