mpc8xxx: LCRR[CLKDIV] is sometimes five bits

On newer CPUs, 8536, 8572, and 8610, the CLKDIV field of LCRR is five bits
instead of four.

In order to avoid an ifdef, LCRR_CLKDIV is set to 0x1f on all systems.  It
should be safe as the fifth bit was defined as reserved and set to 0.

Code that was using a hard coded 0x0f is changed to use LCRR_CLKDIV.

Signed-off-by: Trent Piepho <tpiepho@freescale.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Jon Loeliger <jdl@freescale.com>
diff --git a/board/sbc8548/sbc8548.c b/board/sbc8548/sbc8548.c
index 8c073cb..519b0f7 100644
--- a/board/sbc8548/sbc8548.c
+++ b/board/sbc8548/sbc8548.c
@@ -126,7 +126,7 @@
 	sys_info_t sysinfo;
 
 	get_sys_info(&sysinfo);
-	clkdiv = (lbc->lcrr & 0x0f) * 2;
+	clkdiv = (lbc->lcrr & LCRR_CLKDIV) * 2;
 	lbc_hz = sysinfo.freqSystemBus / 1000000 / clkdiv;
 
 	gur->lbiuiplldcr1 = 0x00078080;