EFM32: Make NVIC functions virtualizable

With CMSIS 5, the NVIC functions are virtualizable. Rename the EFM32
NVIC functions to support being virtualized.

Author: AlessandroA

targets/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32GG_STK3700/device/cmsis_nvic.c

@@ -12,7 +12,7 @@ extern uint32_t __start_vector_table__;		  // Dynamic vector positioning in GCC
 #define NVIC_RAM_VECTOR_ADDRESS (0x20000000)  // Vectors positioned at start of RAM
 #define NVIC_FLASH_VECTOR_ADDRESS (0x0)       // Initial vector position in flash
 
-void NVIC_SetVector(IRQn_Type IRQn, uint32_t vector) {
+void __NVIC_SetVector(IRQn_Type IRQn, uint32_t vector) {
     uint32_t *vectors = (uint32_t*)SCB->VTOR;
     uint32_t i;
 
@@ -41,7 +41,7 @@ void NVIC_SetVector(IRQn_Type IRQn, uint32_t vector) {
     vectors[IRQn + 16] = vector;
 }
 
-uint32_t NVIC_GetVector(IRQn_Type IRQn) {
+uint32_t __NVIC_GetVector(IRQn_Type IRQn) {
     uint32_t *vectors = (uint32_t*)SCB->VTOR;
     return vectors[IRQn + 16];
 }

targets/TARGET_Silicon_Labs/TARGET_EFM32/TARGET_EFM32GG_STK3700/device/cmsis_nvic.h

@@ -16,8 +16,8 @@
 extern "C" {
 #endif
 
-void NVIC_SetVector(IRQn_Type IRQn, uint32_t vector);
-uint32_t NVIC_GetVector(IRQn_Type IRQn);
+void __NVIC_SetVector(IRQn_Type IRQn, uint32_t vector);
+uint32_t __NVIC_GetVector(IRQn_Type IRQn);
 
 #ifdef __cplusplus
 }