fdt: add prototype for fdt_increase_size()

Add a prototype for fdt_increase_size() so that anyone can call it.
Signed-off-by: NTimur Tabi <timur@freescale.com>

include/fdt_support.h

@@ -79,6 +79,7 @@ void ft_pci_setup(void *blob, bd_t *bd);
 
 void set_working_fdt_addr(void *addr);
 int fdt_resize(void *blob);
+int fdt_increase_size(void *fdt, int add_len);
 
 int fdt_fixup_nor_flash_size(void *blob);