timer: Add MPC83xx timer driver

Add a timer driver for the MPC83xx architecture.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 5ab6749..a7d600b 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -140,4 +140,11 @@
 	  Select this to enable support for the timer found on
 	  STM32 devices.
 
+config MPC83XX_TIMER
+        bool "MPC83xx timer support"
+	depends on TIMER
+	help
+	  Select this to enable support for the timer found on
+	  devices based on the MPC83xx family of SoCs.
+
 endmenu