powerpc/powermac/cpufreq_32: Set non-infinite transition time for 7447A driver

The transition time for the 7447A is around 8ms which makes it possible
to use the ondemand governor.  This has been tested on the iBook G4
(PowerBook6,7).
Signed-off-by: NAndreas Schwab <schwab@linux-m68k.org>
Tested-by: NMichel Dänzer <michel@daenzer.net>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/platforms/powermac/cpufreq_32.c

@@ -55,6 +55,7 @@ static unsigned int low_freq;
 static unsigned int hi_freq;
 static unsigned int cur_freq;
 static unsigned int sleep_freq;
+static unsigned long transition_latency;
 
 /*
  * Different models uses different mechanisms to switch the frequency
@@ -403,7 +404,7 @@ static int pmac_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	if (policy->cpu != 0)
 		return -ENODEV;
 
-	policy->cpuinfo.transition_latency	= CPUFREQ_ETERNAL;
+	policy->cpuinfo.transition_latency	= transition_latency;
 	policy->cur = cur_freq;
 
 	cpufreq_frequency_table_get_attr(pmac_cpu_freqs, policy->cpu);
@@ -658,12 +659,14 @@ static int __init pmac_cpufreq_setup(void)
 	if (!value)
 		goto out;
 	cur_freq = (*value) / 1000;
+	transition_latency = CPUFREQ_ETERNAL;
 
 	/*  Check for 7447A based MacRISC3 */
 	if (of_machine_is_compatible("MacRISC3") &&
 	    of_get_property(cpunode, "dynamic-power-step", NULL) &&
 	    PVR_VER(mfspr(SPRN_PVR)) == 0x8003) {
 		pmac_cpufreq_init_7447A(cpunode);
+		transition_latency = 8000000;
 	/* Check for other MacRISC3 machines */
 	} else if (of_machine_is_compatible("PowerBook3,4") ||
 		   of_machine_is_compatible("PowerBook3,5") ||