mtd: nand: Add a helper returning the number of eraseblocks per target

Some drivers in the raw NAND framework seems to need this helper, so
let's just add it instead of open-coding the logic.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Frieder Schrempf <frieder.schrempf@kontron.de>

include/linux/mtd/nand.h

@@ -294,6 +294,18 @@ nanddev_eraseblocks_per_lun(const struct nand_device *nand)
 	return nand->memorg.eraseblocks_per_lun;
 }
 
+/**
+ * nanddev_eraseblocks_per_target() - Get the number of eraseblocks per target
+ * @nand: NAND device
+ *
+ * Return: the number of eraseblocks per target.
+ */
+static inline unsigned int
+nanddev_eraseblocks_per_target(const struct nand_device *nand)
+{
+	return nand->memorg.eraseblocks_per_lun * nand->memorg.luns_per_target;
+}
+
 /**
  * nanddev_target_size() - Get the total size provided by a single target/die
  * @nand: NAND device