mmc: atmel-mci: fix in debugfs: response value printing

In debugfs, printing of command response reports resp[2] twice: fix it to
resp[3].

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>