ARM: rename CONFIG_TIMER_CLK_FREQ to COUNTER_FREQUENCY

Many ARMv8 boards define a constant COUNTER_FREQUENCY to specify the
frequency of the ARM Generic Timer (aka. arch timer).
ARMv7 boards traditionally used CONFIG_TIMER_CLK_FREQ for the same
purpose. It seems useful to unify them.
Since there are less occurences of the latter version, lets convert all
users over to COUNTER_FREQUENCY.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
diff --git a/include/configs/ls1021aqds.h b/include/configs/ls1021aqds.h
index 4fb8b0c..0f239d4 100644
--- a/include/configs/ls1021aqds.h
+++ b/include/configs/ls1021aqds.h
@@ -500,7 +500,7 @@
 #define CONFIG_PEN_ADDR_BIG_ENDIAN
 #define CONFIG_LAYERSCAPE_NS_ACCESS
 #define CONFIG_SMP_PEN_ADDR		0x01ee0200
-#define CONFIG_TIMER_CLK_FREQ		12500000
+#define COUNTER_FREQUENCY		12500000
 
 #define CONFIG_HWCONFIG
 #define HWCONFIG_BUFFER_SIZE		256