CONFIG_MN10300_RTC is not available for thedefaultarchitecture x86.
Result is shown for architecture mn10300

Using MN10300 RTC

modulename: rtc.ko

configname: CONFIG_MN10300_RTC

Linux Kernel Configuration
└─>Panasonic MN10300 system setup
└─>Using MN10300 RTC
In linux kernel since version 2.6.25 (release Date: 2008-04-16)  
This option enables support for the RTC, thus enabling time to be
tracked, even when system is powered down. This is available on-chip
on the MN103E010.

source code:
selects
CONFIG_GENERIC_CMOS_UPDATE