m68k: Let GENERIC_IOMAP depend on HAS_IOPORT

In a future patch HAS_IOPORT=n will disable inb()/outb() and friends at
compile time. With that choosing dynamically between I/O port and MMIO
access via GNERIC_IOMAP will not work. So only select GENERIC_IOMAP when
HAS_IOPORT is selected.

Co-developed-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Niklas Schnelle <[e-mail]>
Reviewed-by: Geert Uytterhoeven <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Geert Uytterhoeven <[e-mail]>

arch/m68k/Kconfig

···
 	select DMA_DIRECT_REMAP if M68K_NONCOHERENT_DMA && !COLDFIRE
 	select GENERIC_ATOMIC64
 	select GENERIC_CPU_DEVICES
-	select GENERIC_IOMAP
+	select GENERIC_IOMAP if HAS_IOPORT
 	select GENERIC_IRQ_SHOW
 	select GENERIC_LIB_ASHLDI3
 	select GENERIC_LIB_ASHRDI3