RISC-V: No need to pass scause as arg to do_IRQ()

The scause is already part of pt_regs so no need to pass
scause as separate arg to do_IRQ().
Reviewed-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAnup Patel <anup@brainfault.org>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/entry.S

@@ -168,7 +168,6 @@ ENTRY(handle_exception)
 
 	/* Handle interrupts */
 	move a0, sp /* pt_regs */
-	move a1, s4 /* scause */
 	tail do_IRQ
 1:
 	/* Exceptions run with interrupts enabled */

arch/riscv/kernel/irq.c

@@ -24,12 +24,12 @@
  */
 #define INTERRUPT_CAUSE_FLAG	(1UL << (__riscv_xlen - 1))
 
-asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs, unsigned long cause)
+asmlinkage void __irq_entry do_IRQ(struct pt_regs *regs)
 {
 	struct pt_regs *old_regs = set_irq_regs(regs);
 
 	irq_enter();
-	switch (cause & ~INTERRUPT_CAUSE_FLAG) {
+	switch (regs->scause & ~INTERRUPT_CAUSE_FLAG) {
 	case INTERRUPT_CAUSE_TIMER:
 		riscv_timer_interrupt();
 		break;