board_f: powerpc: Use timer_init() instead of init_timebase()

There is no good reason to use a different name on PowerPC. Change it to
timer_init() like the others.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: York Sun <york.sun@nxp.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/powerpc/cpu/mpc5xx/cpu_init.c b/arch/powerpc/cpu/mpc5xx/cpu_init.c
index 0f62c13..5bae39f 100644
--- a/arch/powerpc/cpu/mpc5xx/cpu_init.c
+++ b/arch/powerpc/cpu/mpc5xx/cpu_init.c
@@ -43,7 +43,7 @@
 	immr->im_uimb.uimb_umcr = CONFIG_SYS_UMCR;
 
 	/* Time base and decrementer will be enables (TBE) */
-	/* in init_timebase() in time.c called from board_init_f(). */
+	/* in timer_init() in time.c called from board_init_f(). */
 
 	/* Initialize the PIT. Unlock PISCRK */
 	immr->im_sitk.sitk_piscrk = KAPWR_KEY;