Correct alignment of stack top in RISC-V port when configISR_STACK_SIZE_WORDS is defined to a non zero value.

FreeRTOS/Source/portable/GCC/RISC-V/port.c

@@ -56,7 +56,7 @@ stack that was used by main before the scheduler was started for use as the
 interrupt stack after the scheduler has started. */
 #ifdef configISR_STACK_SIZE_WORDS
 	static __attribute__ ((aligned(16))) StackType_t xISRStack[ configISR_STACK_SIZE_WORDS ] = { 0 };
-	const StackType_t xISRStackTop = ( StackType_t ) &( xISRStack[ ( configISR_STACK_SIZE_WORDS & ~portBYTE_ALIGNMENT_MASK ) - 1 ] );
+	const StackType_t xISRStackTop = ( StackType_t ) &( xISRStack[ configISR_STACK_SIZE_WORDS & ~portBYTE_ALIGNMENT_MASK ] );
 #else
 	extern const uint32_t __freertos_irq_stack_top[];
 	const StackType_t xISRStackTop = ( StackType_t ) __freertos_irq_stack_top;