mmc: wmt-sdmmc: Fix settting BM_EIGHTBIT_MODE bit in wmt_mci_set_ios()

For MMC_BUS_WIDTH_8 case, current code missed setting BM_EIGHTBIT_MODE bit.
Also has a small refactor to make the code looks better in readability.

So the bit settings witch below logic:

SDMMC_BUSMODE register:
Set EIGHTBIT_MODE bit for 8 bit mode, Set FOURBIT_MODE bit for 4 bit mode.
Clear both EIGHTBIT_MODE and FOURBIT_MODE bits for 1 bit mode.

SDMMC_EXTCTRL register:
Set EXT_EIGHTBIT bit for 8 bit mode, Clear EXT_EIGHTBIT bit for 1/4 bit mode.

Add define for EXT_EIGHTBIT to avoid using magic number.
BM_ONEBIT_MASK is no longer used, thus remove it.

This patch is untested due to lack of platform with 8-bit hardware.
However since the code is there, it's good to make the code match the document.

Signed-off-by: Axel Lin <[e-mail]>
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/host/wmt-sdmmc.c

···
 #define BM_SPI_CS			0x20
 #define BM_SD_POWER			0x40
 #define BM_SOFT_RESET			0x80
-#define BM_ONEBIT_MASK			0xFD
 
 /* SDMMC_BLKLEN bit fields */
 #define BLKL_CRCERR_ABORT		0x0800
···
 #define STS2_DATARSP_BUSY		0x20
 #define STS2_DIS_FORCECLK		0x80
 
+/* SDMMC_EXTCTRL bit fields */
+#define EXT_EIGHTBIT			0x04
 
 /* MMC/SD DMA Controller Registers */
 #define SDDMA_GCR			0x100
···
 static void wmt_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct wmt_mci_priv *priv;
-	u32 reg_tmp;
+	u32 busmode, extctrl;
 
 	priv = mmc_priv(mmc);
 
···
 	if (ios->clock != 0)
 		clk_set_rate(priv->clk_sdmmc, ios->clock);
 
+	busmode = readb(priv->sdmmc_base + SDMMC_BUSMODE);
+	extctrl = readb(priv->sdmmc_base + SDMMC_EXTCTRL);
+
+	busmode &= ~(BM_EIGHTBIT_MODE | BM_FOURBIT_MODE);
+	extctrl &= ~EXT_EIGHTBIT;
+
 	switch (ios->bus_width) {
 	case MMC_BUS_WIDTH_8:
-		reg_tmp = readb(priv->sdmmc_base + SDMMC_EXTCTRL);
-		writeb(reg_tmp | 0x04, priv->sdmmc_base + SDMMC_EXTCTRL);
+		busmode |= BM_EIGHTBIT_MODE;
+		extctrl |= EXT_EIGHTBIT;
 		break;
 	case MMC_BUS_WIDTH_4:
-		reg_tmp = readb(priv->sdmmc_base + SDMMC_BUSMODE);
-		writeb(reg_tmp | BM_FOURBIT_MODE, priv->sdmmc_base +
-		       SDMMC_BUSMODE);
-
-		reg_tmp = readb(priv->sdmmc_base + SDMMC_EXTCTRL);
-		writeb(reg_tmp & 0xFB, priv->sdmmc_base + SDMMC_EXTCTRL);
+		busmode |= BM_FOURBIT_MODE;
 		break;
 	case MMC_BUS_WIDTH_1:
-		reg_tmp = readb(priv->sdmmc_base + SDMMC_BUSMODE);
-		writeb(reg_tmp & BM_ONEBIT_MASK, priv->sdmmc_base +
-		       SDMMC_BUSMODE);
-
-		reg_tmp = readb(priv->sdmmc_base + SDMMC_EXTCTRL);
-		writeb(reg_tmp & 0xFB, priv->sdmmc_base + SDMMC_EXTCTRL);
 		break;
 	}
+
+	writeb(busmode, priv->sdmmc_base + SDMMC_BUSMODE);
+	writeb(extctrl, priv->sdmmc_base + SDMMC_EXTCTRL);
 }
 
 static int wmt_mci_get_ro(struct mmc_host *mmc)