remoteproc: Keep local copy of firmware name

Storage of the firmware name was inconsistent, either storing a pointer
to a name stored with unknown ownership, or a variable length tacked
onto the end of the struct proc allocated in rproc_alloc.

In preparation for allowing the firmware of an already allocated struct
rproc to be changed, instead always keep a locally maintained copy of
the firmware name.

Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

include/linux/remoteproc.h

@@ -415,7 +415,7 @@ struct rproc {
 	struct list_head node;
 	struct iommu_domain *domain;
 	const char *name;
-	const char *firmware;
+	char *firmware;
 	void *priv;
 	const struct rproc_ops *ops;
 	struct device dev;