os: freertos: remove one linue unused code

* remove one line unused code

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>

Author: Wayne Ren

os/freertos/portable/Synopsys/ARC/arc_support.s

@@ -303,7 +303,6 @@ irq_handler_1:
 	PUSH	blink
 
 	lr	r0, [AUX_IRQ_CAUSE]
-	sr	r0, [AUX_IRQ_SELECT]
 	mov	r1, exc_int_handler_table
 	ld.as	r2, [r1, r0]	/* r2 = exc_int_handler_table + irqno *4 */
 /* handle software triggered interrupt */