Define board_quiesce_devices() in a shared location

This undocumented function relies on arch-specific code to declare a nop
weak version. Add the weak function in common code instead to avoid having
to duplicate the same function in each arch.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

include/bootm.h

@@ -72,4 +72,6 @@ int bootm_decomp_image(int comp, ulong load, ulong image_start, int type,
 		       void *load_buf, void *image_buf, ulong image_len,
 		       uint unc_len, ulong *load_end);
 
+void board_quiesce_devices(void);
+
 #endif