mmc_test: use API to check card type

There are methods to check card type. Let's use them instead of direct checking
type bits.

Signed-off-by: Andy Shevchenko <ext-andriy.shevchenko@nokia.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Chris Ball <cjb@laptop.org>