[CMSIS] Fix SystemCoreClock value.

Source/Templates/system_stm32f1xx.c

diff --git a/Source/Templates/system_stm32f1xx.c b/Source/Templates/system_stm32f1xx.c
index 3e277e6..3afa78d 100644
--- a/Source/Templates/system_stm32f1xx.c
+++ b/Source/Templates/system_stm32f1xx.c
@@ -138,7 +138,7 @@
                is no need to call the 2 first functions listed above, since SystemCoreClock
                variable is updated automatically.
   */
-uint32_t SystemCoreClock = 16000000;
+uint32_t SystemCoreClock = 8000000;
 const uint8_t AHBPrescTable[16U] = {0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 6, 7, 8, 9};
 const uint8_t APBPrescTable[8U] =  {0, 0, 0, 0, 1, 2, 3, 4};