arc: remove unnecessary prom.h includes

Remove unnecessary prom.h includes in preparation to remove prom.h.
Signed-off-by: Rob Herring <rob.herring@calxeda.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Grant Likely <grant.likely@linaro.org>

arch/arc/kernel/devtree.c

@@ -14,7 +14,6 @@
 #include <linux/memblock.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
-#include <asm/prom.h>
 #include <asm/clk.h>
 #include <asm/mach_desc.h>
 

arch/arc/kernel/setup.c

@@ -21,7 +21,6 @@
 #include <asm/setup.h>
 #include <asm/page.h>
 #include <asm/irq.h>
-#include <asm/prom.h>
 #include <asm/unwind.h>
 #include <asm/clk.h>
 #include <asm/mach_desc.h>