arm: Add export.h to ARM specific files as required.

These files all make use of one of the EXPORT_SYMBOL variants
or the THIS_MODULE macro.  So they will need <linux/export.h>

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

arch/arm/mach-omap2/prcm.c

@@ -23,6 +23,7 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/delay.h>
+#include <linux/export.h>
 
 #include <mach/system.h>
 #include <plat/common.h>