ppc4xx: Consolidate PPC4xx UIC defines

This patch is the first step to consolidate the UIC related defines in the
4xx headers. Move header from asm-ppc/ppc4xx-intvec.h to
asm-ppc/ppc4xx-uic.h as it will hold all UIC related defines in the next
steps.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/cpu/ppc4xx/4xx_uart.c b/cpu/ppc4xx/4xx_uart.c
index a7587d4..766e586 100644
--- a/cpu/ppc4xx/4xx_uart.c
+++ b/cpu/ppc4xx/4xx_uart.c
@@ -46,7 +46,7 @@
 #include <asm/processor.h>
 #include <asm/io.h>
 #include <watchdog.h>
-#include <asm/ppc4xx-intvec.h>
+#include <ppc4xx.h>
 
 #ifdef CONFIG_SERIAL_MULTI
 #include <serial.h>