fdt: Export fdtdec_get_number() for general use

This function is missing a prototype but is more widey useful. Add it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/include/fdtdec.h b/include/fdtdec.h
index 11a7b86..967fa88 100644
--- a/include/fdtdec.h
+++ b/include/fdtdec.h
@@ -389,6 +389,17 @@
 		s32 default_val);
 
 /**
+ * Get a variable-sized number from a property
+ *
+ * This reads a number from one or more cells.
+ *
+ * @param ptr	Pointer to property
+ * @param cells	Number of cells containing the number
+ * @return the value in the cells
+ */
+u64 fdtdec_get_number(const fdt32_t *ptr, unsigned int cells);
+
+/**
  * Look up a 64-bit integer property in a node and return it. The property
  * must have at least 8 bytes of data (2 cells). The first two cells are
  * concatenated to form a 8 bytes value, where the first cell is top half and
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 1a0268a..915fe24 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -918,7 +918,7 @@
 	return 0;
 }
 
-static u64 fdtdec_get_number(const fdt32_t *ptr, unsigned int cells)
+u64 fdtdec_get_number(const fdt32_t *ptr, unsigned int cells)
 {
 	u64 number = 0;