Blackfin: cpufreq: use a constant latency

PLL_LOCKCNT applies only to the PLL programming sequence which does not
apply to core and system clock dividers.  Writes to PLL_DIV to change the
CSEL/SSEL dividers take effect immediately.

There is still overhead in software in writing the new dividers, so just
use a value of 50us as this should be good enough.
Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/mach-common/cpufreq.c

@@ -138,7 +138,8 @@ static int __init __bfin_cpu_init(struct cpufreq_policy *policy)
 						 dpm_state_table[index].tscale);
 	}
 
-	policy->cpuinfo.transition_latency = (bfin_read_PLL_LOCKCNT() / (sclk / 1000000)) * 1000;
+	policy->cpuinfo.transition_latency = 50000; /* 50us assumed */
+
 	/*Now ,only support one cpu */
 	policy->cur = cclk;
 	cpufreq_frequency_table_get_attr(bfin_freq_table, policy->cpu);