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/include/asm/irq.h

@@ -13,7 +13,6 @@
 #define TIMER0_IRQ      3
 #define TIMER1_IRQ      4
 
-#include <plat/irq.h>		/* Board Specific IRQ assignments */
 #include <asm-generic/irq.h>
 
 extern void __init arc_init_IRQ(void);