rockchip: make the global board_fit_config_name_match __weak

The core Rockchip spl code contains a default board_fit_config_name_match
implementation doing nothing. Individual boards may want to handle this
differently, so add a __weak atribute to make it possible to override
this function in other places.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

arch/arm/mach-rockchip/spl.c

@@ -147,7 +147,7 @@ void board_init_f(ulong dummy)
 }
 
 #ifdef CONFIG_SPL_LOAD_FIT
-int board_fit_config_name_match(const char *name)
+int __weak board_fit_config_name_match(const char *name)
 {
 	/* Just empty function now - can't decide what to choose */
 	debug("%s: %s\n", __func__, name);