Specify BL31 runtime console for ARM Standard platforms

This patch overrides the default weak definition of
`bl31_plat_runtime_setup()` for ARM Standard platforms to
specify a BL31 runtime console. ARM Standard platforms are
now expected to define `PLAT_ARM_BL31_RUN_UART_BASE` and
`PLAT_ARM_BL31_RUN_UART_CLK_IN_HZ` macros which is required
by `arm_bl31_plat_runtime_setup()` to initialize the runtime
console.

The system suspend resume helper `arm_system_pwr_domain_resume()`
is fixed to initialize the runtime console rather than the boot
console on resumption from system suspend.

Fixes ARM-software/tf-issues#220

Change-Id: I80eafe5b6adcfc7f1fdf8b99659aca1c64d96975
diff --git a/include/plat/arm/common/plat_arm.h b/include/plat/arm/common/plat_arm.h
index aadf58d..ed65d05 100644
--- a/include/plat/arm/common/plat_arm.h
+++ b/include/plat/arm/common/plat_arm.h
@@ -170,6 +170,7 @@
 void arm_bl31_early_platform_setup(bl31_params_t *from_bl2,
 				void *plat_params_from_bl2);
 void arm_bl31_platform_setup(void);
+void arm_bl31_plat_runtime_setup(void);
 void arm_bl31_plat_arch_setup(void);
 
 /* TSP utility functions */