ARM: S5P: Fix the platform external interrupt issues.

This patch does the following:

1. Corrects the common platform code for external interrupts for using the
   VIC mask/unmask bits also.
2. Moves the common defines related to external interrupt for plat-s5p
   to common files.
3. Based on the new common defines, corresponding changes are made in the
   affected platforms (S5P6440, S5P6442 and S5PC100).

Signed-off-by: Pannaga Bhushan <p.bhushan@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>
diff --git a/arch/arm/plat-s5p/Kconfig b/arch/arm/plat-s5p/Kconfig
index 5cb2dd1..11d6a1b 100644
--- a/arch/arm/plat-s5p/Kconfig
+++ b/arch/arm/plat-s5p/Kconfig
@@ -29,3 +29,4 @@
 	bool
 	help
 	  Use the external interrupts (other than GPIO interrupts.)
+	  Note: Do not choose this for S5P6440.