staging: comedi: mite.h: remove "../comedi_pci.h" and make self-reliant

"mite.h" relies on a lot of things declared including "../comedi_pci.h",
but doesn't need anything in "../comedi_pci.h" itself.  None of the
Comedi modules that include "mite.h" rely on it to include
"../comedi_pci.h" on their behalf.

Remove the inclusion of "../comedi_pci.h" from "mite.h", and add enough
other includes and (incomplete) `struct` declarations to make it compile
without warnings or errors even when included first in a .c file.
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Reviewed-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/mite.h

@@ -19,11 +19,17 @@
 #ifndef _MITE_H_
 #define _MITE_H_
 
+#include <linux/io.h>
 #include <linux/log2.h>
-#include "../comedi_pci.h"
+#include <linux/spinlock.h>
 
 #define MAX_MITE_DMA_CHANNELS 8
 
+struct comedi_device;
+struct comedi_subdevice;
+struct device;
+struct pci_dev;
+
 struct mite_dma_descriptor {
 	__le32 count;
 	__le32 addr;