[POWERPC] 4xx: Fix timebase clock selection on Walnut

The current bootwrapper fails to set the timebase clock to the CPU clock
which causes the time to increment incorrectly.  This fixes it by using the
correct #define for the CPC0_CR1 register.
Signed-off-by: NJosh Boyer <jwboyer@linux.vnet.ibm.com>

arch/powerpc/boot/treeboot-walnut.c

@@ -57,8 +57,8 @@ void ibm405gp_fixup_clocks(unsigned int sysclk, unsigned int ser_clk)
 	}
 
 	/* setup the timebase clock to tick at the cpu frequency */
-	cpc0_cr1 = cpc0_cr1 & ~ 0x00800000;
-	mtdcr(DCRN_CPC0_CR1, cpc0_cr1);
+	cpc0_cr1 = cpc0_cr1 & ~0x00800000;
+	mtdcr(DCRN_405_CPC0_CR1, cpc0_cr1);
 	tb = cpu;
 
 	dt_fixup_cpu_clocks(cpu, tb, 0);