sparc64: initialize time early

In Linux it is possible to configure printk() to output timestamp next to
every line. This is very useful to determine the slow parts of the boot
process, and also to avoid regressions, as boot time is visiable to
everyone.

Also, there are scripts that change these time stamps to intervals.

However, on larger machines these timestamps start appearing many seconds,
and even minutes into the boot process. This patch gets stick-frequency
property early from OpenBoot, and uses its value to initialize time stamps
before the first printk() messages are printed.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Reviewed-by: Steven Sistare <steven.sistare@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>