mmc: sdhi: Add EXT_ACC register busy check

All the docs I have access to say that this register needs the bus busy
check.

Signed-off-by: Shinobu Uehara <shinobu.uehara.xc@renesas.com>
Signed-off-by: Ai Kyuse <ai.kyuse.uw@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sh_mobile_sdhi.c

@@ -163,6 +163,7 @@ static int sh_mobile_sdhi_write16_hook(struct tmio_mmc_host *host, int addr)
 	case CTL_SD_MEM_CARD_OPT:
 	case CTL_TRANSACTION_CTL:
 	case CTL_DMA_ENABLE:
+	case EXT_ACC:
 		return sh_mobile_sdhi_wait_idle(host);
 	}