fdt: Update fdt_get_base_address() to use const

This function does not change the device tree so adjust it to use const
for this parameter.

Signed-off-by: Simon Glass <sjg@chromium.org>

common/fdt_support.c

@@ -1539,7 +1539,7 @@ int fdt_verify_alias_address(void *fdt, int anode, const char *alias, u64 addr)
 /*
  * Returns the base address of an SOC or PCI node
  */
-u64 fdt_get_base_address(void *fdt, int node)
+u64 fdt_get_base_address(const void *fdt, int node)
 {
 	int size;
 	u32 naddr;

include/fdt_support.h

@@ -207,7 +207,7 @@ int fdt_add_edid(void *blob, const char *compat, unsigned char *buf);
 
 int fdt_verify_alias_address(void *fdt, int anode, const char *alias,
 			      u64 addr);
-u64 fdt_get_base_address(void *fdt, int node);
+u64 fdt_get_base_address(const void *fdt, int node);
 int fdt_read_range(void *fdt, int node, int n, uint64_t *child_addr,
 		   uint64_t *addr, uint64_t *len);