atmel-mci: Fix memory leak in atmci_regs_show

The debugfs hook atmci_regs_show allocates a temporary buffer for
storing a register snapshot, but it doesn't free it before returning.
Plug this leak.
Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/atmel-mci.c

@@ -218,6 +218,8 @@ static int atmci_regs_show(struct seq_file *s, void *v)
 	atmci_show_status_reg(s, "SR", buf[MCI_SR / 4]);
 	atmci_show_status_reg(s, "IMR", buf[MCI_IMR / 4]);
 
+	kfree(buf);
+
 	return 0;
 }