further fixes for mips ioctl.h header

untested; hopefully it's right now

arch/mips/bits/ioctl.h

@@ -3,10 +3,10 @@
 #define _IOC_READ  2U
 #define _IOC_WRITE 4U
 
-#define _IO(a,b) _IOC(_IOC_NONE,(a),(b),0)
-#define _IOW(a,b,c) _IOC(1,(a),(b),sizeof(c))
-#define _IOR(a,b,c) _IOC(2,(a),(b),sizeof(c))
-#define _IOWR(a,b,c) _IOC(4,(a),(b),sizeof(c))
+#define _IO(a,b) _IOC(1U,(a),(b),0)
+#define _IOW(a,b,c) _IOC(4U,(a),(b),sizeof(c))
+#define _IOR(a,b,c) _IOC(2U,(a),(b),sizeof(c))
+#define _IOWR(a,b,c) _IOC(6U,(a),(b),sizeof(c))
 
 #define TCGETA		0x5401
 #define TCSETA		0x5402