powerpc: Make ppc_md.{halt, restart} __noreturn

powernv marks it's halt and restart calls as __noreturn. However,
ppc_md does not have this annotation. Add the annotation to ppc_md,
and then to every halt/restart function that is missing it.

Additionally, I have verified that all of these functions do not
return. Occasionally I have added a spin loop to be sure.

Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/sysdev/fsl_soc.h

@@ -19,7 +19,7 @@ extern u32 fsl_get_sys_freq(void);
 struct spi_board_info;
 struct device_node;
 
-extern void fsl_rstcr_restart(char *cmd);
+extern void __noreturn fsl_rstcr_restart(char *cmd);
 
 /* The different ports that the DIU can be connected to */
 enum fsl_diu_monitor_port {
@@ -42,8 +42,8 @@ struct platform_diu_data_ops {
 
 extern struct platform_diu_data_ops diu_ops;
 
-void fsl_hv_restart(char *cmd);
-void fsl_hv_halt(void);
+void __noreturn fsl_hv_restart(char *cmd);
+void __noreturn fsl_hv_halt(void);
 
 #endif
 #endif