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/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
index c3acefa..8ac49bd 100644
--- a/arch/powerpc/lib/Makefile
+++ b/arch/powerpc/lib/Makefile
@@ -17,13 +17,17 @@
 
 ifdef MINIMAL
 obj-y += cache.o time.o
+ifndef CONFIG_TIMER
 obj-y += ticks.o
+endif
 else
 
 obj-y	+= ppcstring.o
 
 obj-y	+= ppccache.o
+ifndef CONFIG_TIMER
 obj-y	+= ticks.o
+endif
 obj-y	+= reloc.o
 
 obj-$(CONFIG_BAT_RW) += bat_rw.o