MIPS: generic: Allow boards to set system type

Check for the system_type variable in the get_system_type() function. If
non-NULL, return it as the system type.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/generic/proc.c

@@ -8,11 +8,16 @@
 
 #include <asm/bootinfo.h>
 
+char *system_type;
+
 const char *get_system_type(void)
 {
 	const char *str;
 	int err;
 
+	if (system_type)
+		return system_type;
+
 	err = of_property_read_string(of_root, "model", &str);
 	if (!err)
 		return str;