m68k: virt: Kconfig minor fixes

Select VIRTIO_MENU as it is needed by VIRTIO_MMIO.

Add an ending period at the end of the virt machine help message.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20220531174514.1586248-1-laurent@vivier.euSigned-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/m68k/Kconfig.machine

@@ -161,10 +161,11 @@ config VIRT
 	select RTC_CLASS
 	select RTC_DRV_GOLDFISH
 	select TTY
+	select VIRTIO_MENU
 	select VIRTIO_MMIO
 	help
 	  This options enable a pure virtual machine based on m68k,
-	  VIRTIO MMIO devices and GOLDFISH interfaces (TTY, RTC, PIC)
+	  VIRTIO MMIO devices and GOLDFISH interfaces (TTY, RTC, PIC).
 
 config PILOT
 	bool