PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out

There is another kHz-conversion bug in the code, resulting in integer
overflow. Although, this time the resulting value is 4294966296 and it's
close to ULONG_MAX, which is okay in this case.
Reviewed-by: NChanwoo Choi <cw00.choi@samsung.com>
Tested-by: NPeter Geis <pgwipeout@gmail.com>
Signed-off-by: NDmitry Osipenko <digetx@gmail.com>
Signed-off-by: NChanwoo Choi <cw00.choi@samsung.com>

drivers/devfreq/tegra30-devfreq.c

@@ -69,6 +69,8 @@
 
 #define KHZ							1000
 
+#define KHZ_MAX						(ULONG_MAX / KHZ)
+
 /* Assume that the bus is saturated if the utilization is 25% */
 #define BUS_SATURATION_RATIO					25
 
@@ -170,7 +172,7 @@ struct tegra_actmon_emc_ratio {
 };
 
 static struct tegra_actmon_emc_ratio actmon_emc_ratios[] = {
-	{ 1400000, ULONG_MAX },
+	{ 1400000,    KHZ_MAX },
 	{ 1200000,    750000 },
 	{ 1100000,    600000 },
 	{ 1000000,    500000 },