ARC: [arcfpga] Remove more dead code

specifically after switching to generic early arc uart, whole bunch of
code is no longer needed

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
diff --git a/arch/arc/plat-arcfpga/smp.c b/arch/arc/plat-arcfpga/smp.c
index 92bad91..64797ba 100644
--- a/arch/arc/plat-arcfpga/smp.c
+++ b/arch/arc/plat-arcfpga/smp.c
@@ -13,9 +13,10 @@
 
 #include <linux/smp.h>
 #include <linux/irq.h>
-#include <plat/irq.h>
 #include <plat/smp.h>
 
+#define IDU_INTERRUPT_0 16
+
 static char smp_cpuinfo_buf[128];
 
 /*