mmc: s5p_sdhci: fixed wrong function argument

Useless code is removed, and get buswidth value.
buswidth value will be used to choice the 4bit or 8bit.
(Now used 4bit mode in sdhci.c by default)

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