at_wini: PCI-only now; one controller per instance

- remove non-PCI support, since all supported platforms with at_wini
  devices also have PCI support by now;
- correspondingly, stop using information from the BIOS altogether;
- limit each driver instance to one controller, to be in line with
  the general MINIX3 one-instance-per-controller driver model; this
  limits the number of disks per at_wini instance to four;
- go through the controllers by the order of their occurrence in the
  PCI table, thus removing the exception for compatibility devices;
- let the second at_wini instance shut down silently if there is only
  one IDE controller;
- clean up some extra code we don't need anymore, and resolve some
  WARNS=5 level warnings.

Overall, these changes should simplify automatic loading of the right
disk drivers at boot time in the future.

Change-Id: Ia64d08cfbeb9916abd68c9c2941baeb87d02a806

include/minix/const.h

@@ -93,23 +93,9 @@
 */
 #define NR_MEMS            16
 
-
-/* Click to byte conversions (and vice versa). */
-#define HCLICK_SHIFT       4	/* log2 of HCLICK_SIZE */
-#define HCLICK_SIZE       16	/* hardware segment conversion magic */
-#if CLICK_SIZE >= HCLICK_SIZE
-#define click_to_hclick(n) ((n) << (CLICK_SHIFT - HCLICK_SHIFT))
-#else
-#define click_to_hclick(n) ((n) >> (HCLICK_SHIFT - CLICK_SHIFT))
-#endif
-#define hclick_to_physb(n) ((phys_bytes) (n) << HCLICK_SHIFT)
-#define physb_to_hclick(n) ((n) >> HCLICK_SHIFT)
-
 #define CLICK2ABS(v) ((v) << CLICK_SHIFT)
 #define ABS2CLICK(a) ((a) >> CLICK_SHIFT)
 
-#define ABS             -999	/* this process means absolute memory */
-
 /* Flag bits for i_mode in the inode. */
 #define I_TYPE          0170000	/* this field gives inode type */
 #define I_UNIX_SOCKET	0140000 /* unix domain socket */