hw/isa/vt82c686: Add missing Kconfig dependencies (build error)

hw/isa/vt82c686: Add missing Kconfig dependencies (build error)

The VT82C686 device model misses various dependencies:

  /usr/bin/ld: libcommon.fa.p/hw_isa_vt82c686.c.o: in function `vt82c686b_realize':
  hw/isa/vt82c686.c:622: undefined reference to `i8259_init'
  /usr/bin/ld: hw/isa/vt82c686.c:624: undefined reference to `i8257_dma_init'
  /usr/bin/ld: hw/isa/vt82c686.c:627: undefined reference to `mc146818_rtc_init'

Add them.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: BALATON Zoltan <balaton@eik.bme.hu>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Message-Id: <20210515173716.358295-11-philmd@redhat.com>