RTC: rtc-cmos: Fix binary mode support

As a follow-up to the thread about RTC support for some Loongson 2E/2F
boards, this patch tries to address the "REVISIT"/"FIXME" comments about
rtc binary mode handling and allow rtc to work with rtc in binary mode.
I've also raised the message about 24-h mode not supported to warning
otherwise, one may end up with no rtc without any message in the kernel
log.

Signed-off-by: Arnaud Patard <apatard@mandriva.com>
To: linux-mips@linux-mips.org
To: rtc-linux@googlegroups.com
Cc: david-b@pacbell.net
Cc: a.zummo@towertech.it
Cc: akpm@linux-foundation.org
Patchwork: http://patchwork.linux-mips.org/patch/1158/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>