(Re-)added the Deskpro 386, but only in the development/incomplete section of the code definitions.

Selected XT and AT clones can use either their built-in FDC controller or an external one (the IBM AT and Compaq AT machines don't support booting from a 1.44M floppy so this makes the external floppy useful).
Added the FDC to the Adaptec AHA-154xCF ("2" variant) and defaulted to None to keep compatibility with existing FDC's.

src/include/86box/scsi_x54x.h

@@ -423,7 +423,7 @@ typedef struct {
 		PendingInterrupt, Lock,
 		target_data_len, pad0;
 
-    uint32_t	Base, rom_addr,			/* address of BIOS ROM */
+    uint32_t	Base, fdc_address, rom_addr,			/* address of BIOS ROM */
 		CmdParamLeft, Outgoing,
 		transfer_size;
 
@@ -486,6 +486,8 @@ typedef struct {
     pc_timer_t	timer, ResetCB;
 
     Req_t	Req;
+    
+    fdc_t	*fdc;
 } x54x_t;