Add an implementation of the rtc_enable_32khz_output() that uses the
driver model i2c APIs.
Also put code related to rtc_enable_32khz_output
under CONFIG_RTC_ENABLE_32KHZ_OUTPUT.
Signed-off-by: Chuanhua Han <chuanhua.han@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>