[PATCH] rtc-rs5c372: change register reading method

According to the datasheet rs5c372 supports three different methods for
reading register values.  Change from method #1 to method #3, since method #3
is the only one that works on Thecus N2100 board with this RTC.

Signed-off-by: Riku Voipio <riku.voipio@movial.fi>
Cc: Alessandro Zummo <alessandro.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>