net: via/Kconfig: GENERIC_PCI_IOMAP required if PCI not selected

The builds of allmodconfig of avr32 is failing with:

drivers/net/ethernet/via/via-rhine.c:1098:2: error: implicit declaration
of function 'pci_iomap' [-Werror=implicit-function-declaration]
drivers/net/ethernet/via/via-rhine.c:1119:2: error: implicit declaration
of function 'pci_iounmap' [-Werror=implicit-function-declaration]

The generic empty pci_iomap and pci_iounmap is used only if CONFIG_PCI
is not defined and CONFIG_GENERIC_PCI_IOMAP is defined.

Add GENERIC_PCI_IOMAP in the dependency list for VIA_RHINE as we are
getting build failure when CONFIG_PCI and CONFIG_GENERIC_PCI_IOMAP both
are not defined.

Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: David S. Miller <davem@davemloft.net>