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/MAINTAINERS b/MAINTAINERS
index 1aab4b3..e23abaf 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -526,6 +526,7 @@
 F:	drivers/clk/mpc83xx_clk.c
 F:	drivers/clk/mpc83xx_clk.h
 F:	include/dt-bindings/clk/mpc83xx-clk.h
+F:	drivers/timer/mpc83xx_timer.c
 F:	arch/powerpc/cpu/mpc83xx/
 F:	arch/powerpc/include/asm/arch-mpc83xx/