MIPS: bcm63xx: cpu: Replace BUG() with panic()

BUG() can be a noop if CONFIG_BUG is not selected,
leading to the following build problem on a randconfig:

arch/mips/bcm63xx/cpu.c: In function 'detect_cpu_clock':
arch/mips/bcm63xx/cpu.c:254:1: error: control reaches end of
non-void function [-Werror=return-type]

We fix this problem by replacing BUG() with panic() since it's
best to handle the case of an unknown board instead of silently
returning a random clock frequency.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Acked-by: Jonas Gorski <jogo@openwrt.org>
Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/5932/

arch/mips/bcm63xx/cpu.c

@@ -123,7 +123,9 @@ unsigned int bcm63xx_get_memory_size(void)
 
 static unsigned int detect_cpu_clock(void)
 {
-	switch (bcm63xx_get_cpu_id()) {
+	u16 cpu_id = bcm63xx_get_cpu_id();
+
+	switch (cpu_id) {
 	case BCM3368_CPU_ID:
 		return 300000000;
 
@@ -249,7 +251,7 @@ static unsigned int detect_cpu_clock(void)
 	}
 
 	default:
-		BUG();
+		panic("Failed to detect clock for CPU with id=%04X\n", cpu_id);
 	}
 }