cmd: fuse: Add fuse writebuff sub-system command

Add CMD_FUSE_WRITEBUFF config option to add and enable fuse writebuff
sub-system command. Add fuse_writebuff function to be invoked on
writebuff command.

Signed-off-by: Harsha Vardhan V M <h-vm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/include/fuse.h b/include/fuse.h
index 4519821..902b5f5 100644
--- a/include/fuse.h
+++ b/include/fuse.h
@@ -12,6 +12,7 @@
 #define _FUSE_H_
 
 #include <linux/types.h>
+#include <linux/errno.h>
 
 /*
  * Read/Sense/Program/Override interface:
@@ -25,5 +26,13 @@
 int fuse_sense(u32 bank, u32 word, u32 *val);
 int fuse_prog(u32 bank, u32 word, u32 val);
 int fuse_override(u32 bank, u32 word, u32 val);
+#ifdef CONFIG_CMD_FUSE_WRITEBUFF
+int fuse_writebuff(ulong addr);
+#else
+static inline int fuse_writebuff(ulong addr)
+{
+	return -EPERM;
+}
+#endif	/* CONFIG_CMD_FUSE_WRITEBUFF */
 
 #endif	/* _FUSE_H_ */