[NET] smc91x: Make smc91x use IRQ resource trigger flags

smc91x is shared between many different platforms.  Each platform needs
to specify the interrupt type, and in some cases the irq type depends
on more than just the build configuration - it depends on runtime
checks.

Rather than throwing this code into the SMC_IRQ_FLAGS definition, provide
a way for these flags to be passed via the IRQ resource itself.

Note that IRQF_TRIGGER_* constants are intentionally defined to correspond
with the IORESOURCE_IRQ_* interrupt type flags, in much the same way that
the low bits of PCI iomem resources correspond with the BAR flag bits.

Also provide a way to configure smc91x to read the IRQ flags from the
resource.  Once all platforms have been converted over (signified
by all definitions of SMC_IRQ_FLAGS being -1) SMC_IRQ_FLAGS should
be removed.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Nicolas Pitre <nico@cam.org>
Acked-by: Jeff Garzik <jgarzik@redhat.com>