Tweak AVR critical section defines

Marlin/src/HAL/HAL_AVR/HAL.h

 //#define analogInputToDigitalPin(IO) IO
 
 #ifndef CRITICAL_SECTION_START
-  #define CRITICAL_SECTION_START  unsigned char _sreg = SREG; cli();
-  #define CRITICAL_SECTION_END    SREG = _sreg;
+  #define CRITICAL_SECTION_START  unsigned char _sreg = SREG; cli()
+  #define CRITICAL_SECTION_END    SREG = _sreg
 #endif
 #define ISRS_ENABLED() TEST(SREG, SREG_I)
 #define ENABLE_ISRS()  sei()