mmc: core: simplify return code

File contains multiple functions doing variations on the same thing,
sdio_readb(), sdio_writeb()f, sdio_readw(), sdio_writew()
etc. Although the functions have very similar logic the code is laid
out in a variety of ways. This makes it overly complicated to
read. There is a already a nice clean chunk of code, if we use this
format for all instances then we will have cleaned up the code,
reduced the line count and lessened the cognitive load required while
reading. Less lines equals less bugs.

Pick the most simple and clear code flow and change all functions to
be the same.

Signed-off-by: Tobin C. Harding <[e-mail]>
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/core/sdio_io.c

···
 		return 0xFF;
 	}
 
-	if (err_ret)
-		*err_ret = 0;
-
 	ret = mmc_io_rw_direct(func->card, 0, func->num, addr, 0, &val);
-	if (ret) {
-		if (err_ret)
-			*err_ret = ret;
+	if (err_ret)
+		*err_ret = ret;
+	if (ret)
 		return 0xFF;
-	}
 
 	return val;
 }
···
 	if (err_ret)
 		*err_ret = ret;
 	if (ret)
-		val = 0xff;
+		return 0xff;
 
 	return val;
 }
···
 {
 	int ret;
 
-	if (err_ret)
-		*err_ret = 0;
-
 	ret = sdio_memcpy_fromio(func, func->tmpbuf, addr, 2);
-	if (ret) {
-		if (err_ret)
-			*err_ret = ret;
+	if (err_ret)
+		*err_ret = ret;
+	if (ret)
 		return 0xFFFF;
-	}
 
 	return le16_to_cpup((__le16 *)func->tmpbuf);
 }
···
 {
 	int ret;
 
-	if (err_ret)
-		*err_ret = 0;
-
 	ret = sdio_memcpy_fromio(func, func->tmpbuf, addr, 4);
-	if (ret) {
-		if (err_ret)
-			*err_ret = ret;
+	if (err_ret)
+		*err_ret = ret;
+	if (ret)
 		return 0xFFFFFFFF;
-	}
 
 	return le32_to_cpup((__le32 *)func->tmpbuf);
 }
···
 		return 0xFF;
 	}
 
-	if (err_ret)
-		*err_ret = 0;
-
 	ret = mmc_io_rw_direct(func->card, 0, 0, addr, 0, &val);
-	if (ret) {
-		if (err_ret)
-			*err_ret = ret;
+	if (err_ret)
+		*err_ret = ret;
+	if (ret)
 		return 0xFF;
-	}
 
 	return val;
 }