According to the README, CONFIG_SYS_HZ must be 1000 and most platforms
follow that. In preparation to remove CONFIG_SYS_HZ from all these
platforms, provide a common definition. The platforms which use a value
other than 1000 will get build warning now. These configs are:

include/configs/M5271EVB.h:#define CONFIG_SYS_HZ                        1000000
include/configs/balloon3.h:#define      CONFIG_SYS_HZ                   3250000         /* Timer @ 3250000 Hz */
include/configs/idmr.h:#define CONFIG_SYS_HZ                    (50000000 / 64)
include/configs/mini2440.h:#define CONFIG_SYS_HZ                        1562500
include/configs/mx1ads.h:#define CONFIG_SYS_HZ                  3686400
include/configs/omap3_zoom2.h:#define CONFIG_SYS_HZ                     ((V_SCLK) / (2 << CONFIG_SYS_PTV))
include/configs/omap730p2.h:#define CONFIG_SYS_HZ                       ((CONFIG_SYS_CLK_FREQ)/(2 << CONFIG_SYS_PTV))
include/configs/palmld.h:#define        CONFIG_SYS_HZ                   3250000         /* Timer @ 3250000 Hz */
include/configs/palmtc.h:#define        CONFIG_SYS_HZ                   3686400         /* Timer @ 3686400 Hz */
include/configs/rsk7203.h:#define CONFIG_SYS_HZ                 (CONFIG_SYS_CLK_FREQ / CMT_CLK_DIVIDER)
include/configs/rsk7264.h:#define CONFIG_SYS_HZ         (CONFIG_SYS_CLK_FREQ / CMT_CLK_DIVIDER)
include/configs/rsk7269.h:#define CONFIG_SYS_HZ         (CONFIG_SYS_CLK_FREQ / CMT_CLK_DIVIDER)
include/configs/scb9328.h:#define CONFIG_SYS_HZ                 3686400      /* incrementer freq: 3.6864 MHz */
include/configs/versatile.h:#define CONFIG_SYS_HZ                       (1000000 / 256)
include/configs/zipitz2.h:#define       CONFIG_SYS_HZ                   3250000         /* Timer @ 3250000 Hz */

Signed-off-by: Rob Herring <rob.herring@calxeda.com>