DS1339 manual, page 6, chapter Date and time operation:
  The DS1339 can be run in either 12-hour or 24-hour mode. Bit 6 of the
  hours register is defined as the 12-hour or 24-hour mode-select bit.
  When high, the 12-hour mode is selected.

Patch below makes ds1337 driver work as documented in manual.
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>