cpufreq: dt: Update kconfig description

The cpufreq DT driver also supports systems that have multiple
clock/voltage domains for CPUs, i.e. multiple policy systems.

The description of the Kconfig entry was never updated after the driver
was modified to support such systems, fix it.
Reported-by: NJuri Lelli <Juri.Lelli@arm.com>
Signed-off-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/Kconfig

@@ -225,7 +225,7 @@ config CPUFREQ_DT
 	help
 	  This adds a generic DT based cpufreq driver for frequency management.
 	  It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
-	  systems which share clock and voltage across all CPUs.
+	  systems.
 
 	  If in doubt, say N.