set_rtc_mmss: show warning message only once

set_rtc_mmss: show warning message only once

Occasionally the system gets into a state where the CMOS clock has gotten
slightly ahead of current time and the periodic update of RTC fails.  The
message is a nuisance and repeats spamming the log.

  See: http://www.ntp.org/ntpfaq/NTP-s-trbl-spec.htm#Q-LINUX-SET-RTC-MMSS

Rather than just removing the message, make it show only once and reduce
severity since it indicates a normal and non urgent condition.

Signed-off-by: Stephen Hemminger <[email protected]>
Cc: Richard Henderson <[email protected]>
Cc: Ivan Kokshaysky <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: David Howells <[email protected]>
Cc: Paul Mundt <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>