mtd: spi-nor: Separate preparation and locking

While this operation will remain a single function call in the end,
let's extract the logic of the [un]prepare calls within their own static
helper. We will soon add new flavors of the *_[un]prepare_and_[un]lock()
helpers, having the preparation logic outside will save us from duplicating
code over and over again.

There is no functional change.

Signed-off-by: Miquel Raynal <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Tudor Ambarus <[email protected]>

drivers/mtd/spi-nor/core.c

@@ -1070,24 +1070,40 @@ static void spi_nor_set_4byte_opcodes(struct spi_nor *nor)
 	}
 }
 
-int spi_nor_prep_and_lock(struct spi_nor *nor)
+static int spi_nor_prep(struct spi_nor *nor)
 {
 	int ret = 0;
 
 	if (nor->controller_ops && nor->controller_ops->prepare)
 		ret = nor->controller_ops->prepare(nor);
 
+	return ret;
+}
+
+static void spi_nor_unprep(struct spi_nor *nor)
+{
+	if (nor->controller_ops && nor->controller_ops->unprepare)
+		nor->controller_ops->unprepare(nor);
+}
+
+int spi_nor_prep_and_lock(struct spi_nor *nor)
+{
+	int ret;
+
+	ret = spi_nor_prep(nor);
+	if (ret)
+		return ret;
+
 	mutex_lock(&nor->lock);
 
-	return ret;
+	return 0;
 }
 
 void spi_nor_unlock_and_unprep(struct spi_nor *nor)
 {
 	mutex_unlock(&nor->lock);
 
-	if (nor->controller_ops && nor->controller_ops->unprepare)
-		nor->controller_ops->unprepare(nor);
+	spi_nor_unprep(nor);
 }
 
 static u32 spi_nor_convert_addr(struct spi_nor *nor, loff_t addr)