rtc: max77686: Cleanup and reduce dmesg output

Cleanup of entire driver of its dmesg output:
1. Remove printing of the function name, because printing device name is
   sufficient. This also makes the dev_err()-like functions more compact
   and readable (not need of line break).
2. Lower from info to debug printing of each RTC interrupt (no need to
   make noise on each alarm).
3. Remove dev_info() at beginning of probe because a message is already
   always printed by either probe failure or from registering the RTC
   device as /dev/rtcX.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>