mtd: core: provide unique name for nvmem device, take two

commit 1cd9cea upstream.

Commit c048b60 ("mtd: core: provide unique name for nvmem device")
tries to give the nvmem device a unique name, but fails badly if the mtd
device doesn't have a "struct device" associated with it, i.e. if
CONFIG_MTD_PARTITIONED_MASTER is not set. This will result in the name
"(null)-user-otp", which is not unique. It seems the best we can do is
to use the compatible name together with a unique identifier added by
the nvmem subsystem by using NVMEM_DEVID_AUTO.

Fixes: c048b60 ("mtd: core: provide unique name for nvmem device")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20230308082021.870459-1-michael@walle.cc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/mtd/mtdcore.c

@@ -888,8 +888,8 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 
 	/* OTP nvmem will be registered on the physical device */
 	config.dev = mtd->dev.parent;
-	config.name = kasprintf(GFP_KERNEL, "%s-%s", dev_name(&mtd->dev), compatible);
-	config.id = NVMEM_DEVID_NONE;
+	config.name = compatible;
+	config.id = NVMEM_DEVID_AUTO;
 	config.owner = THIS_MODULE;
 	config.type = NVMEM_TYPE_OTP;
 	config.root_only = true;
@@ -905,7 +905,6 @@ static struct nvmem_device *mtd_otp_nvmem_register(struct mtd_info *mtd,
 		nvmem = NULL;
 
 	of_node_put(np);
-	kfree(config.name);
 
 	return nvmem;
 }