ARC: [Review] Multi-platform image #4: Isolate platform headers

-Top level ARC makefile removes -I for platform headers
-asm/irq.h no longer includes plat/irq.h

-platform makefile adds -I for it's specfic platform headers
-platform code to directly include it's plat/irq.h

-Linker script needed plat/memmap.h for CCM info, already in .config

Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/arc/plat-arcfpga/irq.c

@@ -9,7 +9,7 @@
  */
 
 #include <linux/interrupt.h>
-#include <asm/irq.h>
+#include <plat/irq.h>
 
 void __init plat_fpga_init_IRQ(void)
 {