rtc:ds3232/ds3231: Add support to generate 32KHz output

RTC devices can generate 32KHz output if for
-DS3232 device, EN32KHz bit and BB32KHz bit are set
-DS3231 device, EN32KHz bit is set, BB32KHz bit is don't care

Patch adds rtc_enable_32khz_output() which when called
will enable 32KHz output on 32KHz pin

Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>
2 files changed