serial: reduce include platform file for marvell chip

Build pass with following config:
dkb_config
aspenite_config
edminiv2_config
openrd_ultimate_config
sheevaplug_config
mv88f6281gtw_ge_config
rd6281a_config
guruplug_config
km_kirkwood_config

Signed-off-by: Lei Wen <leiwen@marvell.com>
Acked-by: Wolfgang Denk <wd@denx.de>

drivers/serial/serial.c

@@ -28,15 +28,6 @@
 #ifdef CONFIG_NS87308
 #include <ns87308.h>
 #endif
-#ifdef CONFIG_KIRKWOOD
-#include <asm/arch/kirkwood.h>
-#elif defined(CONFIG_ORION5X)
-#include <asm/arch/orion5x.h>
-#elif defined(CONFIG_ARMADA100)
-#include <asm/arch/armada100.h>
-#elif defined(CONFIG_PANTHEON)
-#include <asm/arch/pantheon.h>
-#endif
 
 #if defined (CONFIG_SERIAL_MULTI)
 #include <serial.h>