drivers/rtc/rtc-efi.c: fix section mismatch warning

efi_rtc_init() uses platform_driver_probe(), so there's no need to also
set efi_rtc_driver's probe member (as it won't be used anyway).  This
fixes a modpost section mismatch warning (as efi_rtc_probe() validly is
__init).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Matthew Garrett <mjg@redhat.com>
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>