RISC-V: Don't include irq-riscv-intc.h

This file has never existed in the upstream kernel, but it's guarded by
an #ifdef that's also never existed in the upstream kernel.  As a part
of our interrupt controller refactoring this header is no longer
necessary, but this reference managed to sneak in anyway.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

arch/riscv/kernel/irq.c

@@ -16,10 +16,6 @@
 #include <linux/irqchip.h>
 #include <linux/irqdomain.h>
 
-#ifdef CONFIG_RISCV_INTC
-#include <linux/irqchip/irq-riscv-intc.h>
-#endif
-
 void __init init_IRQ(void)
 {
 	irqchip_init();