hw/i386/vmport: Define enum for all commands

No functional change.

Defining an enum for all VMPort commands have the following advantages:
* It gets rid of the error-prone requirement to update VMPORT_ENTRIES
when new VMPort commands are added to QEMU.
* It makes it clear to know by looking at one place at the source, what
are all the VMPort commands supported by QEMU.

Reviewed-by: Nikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200312165431.82118-9-liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/hw/i386/vmport.h

@@ -6,11 +6,20 @@
 #define TYPE_VMPORT "vmport"
 typedef uint32_t (VMPortReadFunc)(void *opaque, uint32_t address);
 
+typedef enum {
+    VMPORT_CMD_GETVERSION       = 10,
+    VMPORT_CMD_GETRAMSIZE       = 20,
+    VMPORT_CMD_VMMOUSE_DATA     = 39,
+    VMPORT_CMD_VMMOUSE_STATUS   = 40,
+    VMPORT_CMD_VMMOUSE_COMMAND  = 41,
+    VMPORT_ENTRIES
+} VMPortCommand;
+
 static inline void vmport_init(ISABus *bus)
 {
     isa_create_simple(bus, TYPE_VMPORT);
 }
 
-void vmport_register(unsigned char command, VMPortReadFunc *func, void *opaque);
+void vmport_register(VMPortCommand command, VMPortReadFunc *func, void *opaque);
 
 #endif