staging:rts_pstor:Fix SDIO issue

Fix a bug that SDIO and SD normal card would appear simultaneously if a SDIO card inserted.

Signed-off-by: wwang <wei_wang@realsil.com.cn>
Acked-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>