drivers/rtc/Kconfig: disable RTC_DRV_CMOS on Atari

On ARAnyM (emulating an Atari Falcon, which doesn't have an RTC IRQ, as
the Second Multi Function Peripheral MFP 68901 is available on Atari TT
only), rtc-cmos doesn't work well:

  - The date is of by 32 years (2045 instead of 2013):

    rtc_cmos rtc_cmos: setting system clock to 2045-12-02 10:56:17 UTC
    (2395824977)

  - The hwclock utility doesn't work:

    hwclock: ioctl() to /dev/rtc to turn on update interrupts failed
    unexpectedly, errno=5: Input/output error.

As rtc-generic works fine for the RTC part, and nvram works for the NVRAM
part, we'll continue on using that.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>