staging: comedi: mite.h: remove mite_irq()

This inline function simply returns the 'irq' of the struct pci_dev pointer
that is stored in struct mite_struct. This pci_dev pointer is the same as
the one that is already available in the (*auto_attach) functions where
mite_irq() is used.

Use the pci_dev pointer directly to get the irq and remove the unnecessary
inline function to remove the indirection.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>