rtc: pcf8563: fix write of invalid bits to ST2 reg
rtc: pcf8563: fix write of invalid bits to ST2 reg

The NXP datasheet says:
 "Bits labeled as N should always be written with logic 0."

At least one of those bits is sometime read as a 1, therfore violating
this rule.  To fix this we mask away those bits.

Signed-off-by: Jan Kardell <d7513ec1675053b4642241f505869539ec82459f@telliq.com>
Cc: Alessandro Zummo <f0b9bd96bf07bfecc189c62159960134588fafe5@towertech.it>
Cc: Grant Likely <9069e6f5a2b566e2674a0ba1e2bf39c12c195fad@linaro.org>
Cc: Rob Herring <988782c95b9025801edfc9a5b1fd5a8e93699e07@kernel.org>
Cc: Vincent Donnefort <cfb877cc55bc8fd3927edda486d7ee2c9774fd8d@gmail.com>
Cc: Dan Carpenter <ff341aa343d564f9e53e9dcb6996be8c04859a66@oracle.com>
Signed-off-by: Andrew Morton <5c1e68b099950c134891f0b6e179498a8ebe9cf9@linux-foundation.org>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs