remoteproc: Use kstrdup_const() rather than kstrdup()

For cases where @firmware is declared "const char *", use function
kstrdup_const() to avoid needlessly creating another copy on the
heap.
Suggested-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20200420231601.16781-2-mathieu.poirier@linaro.orgSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/remoteproc_core.c

@@ -1996,7 +1996,7 @@ static void rproc_type_release(struct device *dev)
 	if (rproc->index >= 0)
 		ida_simple_remove(&rproc_dev_index, rproc->index);
 
-	kfree(rproc->firmware);
+	kfree_const(rproc->firmware);
 	kfree(rproc->ops);
 	kfree(rproc);
 }
@@ -2009,7 +2009,7 @@ static const struct device_type rproc_type = {
 static int rproc_alloc_firmware(struct rproc *rproc,
 				const char *name, const char *firmware)
 {
-	char *p;
+	const char *p;
 
 	if (!firmware)
 		/*
@@ -2018,7 +2018,7 @@ static int rproc_alloc_firmware(struct rproc *rproc,
 		 */
 		p = kasprintf(GFP_KERNEL, "rproc-%s-fw", name);
 	else
-		p = kstrdup(firmware, GFP_KERNEL);
+		p = kstrdup_const(firmware, GFP_KERNEL);
 
 	if (!p)
 		return -ENOMEM;
@@ -2122,7 +2122,7 @@ struct rproc *rproc_alloc(struct device *dev, const char *name,
 	return rproc;
 
 free_firmware:
-	kfree(rproc->firmware);
+	kfree_const(rproc->firmware);
 free_rproc:
 	kfree(rproc);
 	return NULL;

include/linux/remoteproc.h

@@ -489,7 +489,7 @@ struct rproc {
 	struct list_head node;
 	struct iommu_domain *domain;
 	const char *name;
-	char *firmware;
+	const char *firmware;
 	void *priv;
 	struct rproc_ops *ops;
 	struct device dev;