libfdt: Add fdt_getprop_namelen_w

Add a function to retrieve a writeable property only by the first
characters of its name.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>

include/libfdt.h

@@ -619,6 +619,13 @@ const void *fdt_getprop_by_offset(const void *fdt, int offset,
  */
 const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
 				const char *name, int namelen, int *lenp);
+static inline void *fdt_getprop_namelen_w(void *fdt, int nodeoffset,
+					  const char *name, int namelen,
+					  int *lenp)
+{
+	return (void *)(uintptr_t)fdt_getprop_namelen(fdt, nodeoffset, name,
+						      namelen, lenp);
+}
 
 /**
  * fdt_getprop - retrieve the value of a given property