vfio/pci: zap_vma_ptes() needs MMU

zap_vma_ptes() is only available when CONFIG_MMU is set/enabled.
Without CONFIG_MMU, vfio_pci.o has build errors, so make
VFIO_PCI depend on MMU.

riscv64-linux-ld: drivers/vfio/pci/vfio_pci.o: in function `vfio_pci_mmap_open':
vfio_pci.c:(.text+0x1ec): undefined reference to `zap_vma_ptes'
riscv64-linux-ld: drivers/vfio/pci/vfio_pci.o: in function `.L0 ':
vfio_pci.c:(.text+0x165c): undefined reference to `zap_vma_ptes'

Fixes: 11c4cd0 ("vfio-pci: Fault mmaps to enable vma tracking")
Signed-off-by: Randy Dunlap <[email protected]>
Reported-by: kernel test robot <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Cornelia Huck <[email protected]>
Cc: [email protected]
Cc: Jason Gunthorpe <[email protected]>
Cc: Eric Auger <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Alex Williamson <[email protected]>

Author: rddunlap

drivers/vfio/pci/Kconfig

@@ -2,6 +2,7 @@
 config VFIO_PCI
 	tristate "VFIO support for PCI devices"
 	depends on VFIO && PCI && EVENTFD
+	depends on MMU
 	select VFIO_VIRQFD
 	select IRQ_BYPASS_MANAGER
 	help