MIPS: BMIPS: Utilize cfe_die() for invalid DTB

If we were not specified a correct DTB, we will not be able to print
anything useful with panic() which requires a working console of some
sort. Utilize cfe_die() to callback into the CFE default UART and print
some useful diagnostics.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/Kconfig

@@ -294,6 +294,7 @@ config BMIPS_GENERIC
 	select HARDIRQS_SW_RESEND
 	select HAVE_PCI
 	select PCI_DRIVERS_GENERIC
+	select FW_CFE
 	help
 	  Build a generic DT-based kernel image that boots on select
 	  BCM33xx cable modem chips, BCM63xx DSL chips, and BCM7xxx set-top

arch/mips/bmips/setup.c

@@ -28,6 +28,7 @@
 #include <asm/smp-ops.h>
 #include <asm/time.h>
 #include <asm/traps.h>
+#include <asm/fw/cfe/cfe_api.h>
 
 #define RELO_NORMAL_VEC		BIT(18)
 
@@ -123,8 +124,19 @@ static const struct bmips_quirk bmips_quirk_list[] = {
 	{ },
 };
 
+static void __init bmips_init_cfe(void)
+{
+	cfe_seal = fw_arg3;
+
+	if (cfe_seal != CFE_EPTSEAL)
+		return;
+
+	cfe_init(fw_arg0, fw_arg2);
+}
+
 void __init prom_init(void)
 {
+	bmips_init_cfe();
 	bmips_cpu_setup();
 	register_bmips_smp_ops();
 }
@@ -165,7 +177,7 @@ void __init plat_mem_setup(void)
 		dtb = get_fdt();
 
 	if (!dtb)
-		panic("no dtb found");
+		cfe_die("no dtb found");
 
 	__dt_setup_arch(dtb);