Report our devices as "MFM drives" so that Finder shows a 3.5" floppy icon.

Previously, we had actually been (erroneously) using the code for a generic hard drive, rather than a generic floppy as intended. The generic floppy code shows a 5.25" floppy icon, which seems less appropriate, so now we use the same code as 3.5" SuperDrives instead.

driver.c

@@ -42,7 +42,7 @@ void InitDIBs(void) {
         dibs[i].slotNum = 0x8003;
         dibs[i].unitNum = i+1;
         dibs[i].version = DRIVER_VERSION;
-        dibs[i].deviceID = DEVICE_GENERIC_FLOPPY_DRIVE;
+        dibs[i].deviceID = DEVICE_MFM_DRIVE;
         
         dibList.dibPointers[i] = &dibs[i];
     }

driver.h

@@ -3,7 +3,7 @@
 
 #include <types.h>
 
-#define DEVICE_GENERIC_FLOPPY_DRIVE 0x0013
+#define DEVICE_MFM_DRIVE 0x0017  /* This is the ID used for FDHD SuperDrives */
 
 #define NDIBS 16