3c515: fix using pnp_get_resource when CONFIG_ISAPNP=n

3c515.c uses pnp_irq(), which calls pnp_get_resource(),
which is not defined when CONFIG_PNP=n, so in that case,
get the IRQ from a hardware register.

3c515.c:(.text+0x3adc0): undefined reference to `pnp_get_resource'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>