common: Add new clk command

Command provides just dump subcommand for showing clock
frequencies in a soc.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Stefano Babic <sbabic@denx.de>

include/config_cmd_all.h

@@ -23,6 +23,7 @@
 #define CONFIG_CMD_BSP		/* Board Specific functions	*/
 #define CONFIG_CMD_CACHE	/* icache, dcache		*/
 #define CONFIG_CMD_CDP		/* Cisco Discovery Protocol	*/
+#define CONFIG_CMD_CLK		/* Clock support		*/
 #define CONFIG_CMD_CONSOLE	/* coninfo			*/
 #define CONFIG_CMD_DATE		/* support for RTC, date/time...*/
 #define CONFIG_CMD_DHCP		/* DHCP Support			*/