s390: drop CONFIG_VIRT_TO_BUS

VIRT_TO_BUS is only used for legacy device PCI and ISA drivers using
virt_to_bus() instead of the streaming DMA mapping API, and the
remaining drivers generally don't work on 64-bit architectures.

Two of these drivers also cause a build warning on s390, so instead
of trying to fix that, let's just disable the option as we do on
most architectures now.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/Kconfig

@@ -189,7 +189,6 @@ config S390
 	select TTY
 	select VIRT_CPU_ACCOUNTING
 	select ARCH_HAS_SCALED_CPUTIME
-	select VIRT_TO_BUS
 	select HAVE_NMI