pstore: make pstore write function return normal success/fail value

Currently pstore write interface employs record id as return
value, but it is not enough because it can't tell caller if
the write operation is successful. Pass the record id back via
an argument pointer and return zero for success, non-zero for
failure.

Signed-off-by: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
diff --git a/include/linux/pstore.h b/include/linux/pstore.h
index b91440e..ea56732 100644
--- a/include/linux/pstore.h
+++ b/include/linux/pstore.h
@@ -39,8 +39,8 @@
 	int		(*close)(struct pstore_info *psi);
 	ssize_t		(*read)(u64 *id, enum pstore_type_id *type,
 			struct timespec *time, struct pstore_info *psi);
-	u64		(*write)(enum pstore_type_id type, unsigned int part,
-			size_t size, struct pstore_info *psi);
+	int		(*write)(enum pstore_type_id type, u64 *id,
+			unsigned int part, size_t size, struct pstore_info *psi);
 	int		(*erase)(enum pstore_type_id type, u64 id,
 			struct pstore_info *psi);
 	void		*data;