Make extra_features canonical

Author: stefanrueger

src/avrdude.conf.in

@@ -2982,7 +2982,7 @@ programmer # pickit4
     desc                   = "MPLAB(R) PICkit 4 in JTAG mode";
     type                   = "jtagice3";
     prog_modes             = PM_JTAG | PM_XMEGAJTAG;
-    extra_features         = HAS_VTARG_READ | HAS_VTARG_READ | HAS_BITCLOCK_ADJ;
+    extra_features         = HAS_VTARG_READ | HAS_BITCLOCK_ADJ;
     connection_type        = usb;
     usbvid                 = 0x03eb;
     usbpid                 = 0x2177, 0x2178, 0x2179;
@@ -3034,7 +3034,7 @@ programmer parent "pickit4" # pickit4_tpi
     desc                   = "MPLAB(R) PICkit 4 in TPI mode";
     type                   = "jtagice3_tpi";
     prog_modes             = PM_TPI;
-    extra_features         = HAS_VTARG_READ | HAS_VTARG_READ;
+    extra_features         = HAS_VTARG_READ;
 ;
 
 # End of "Atmel" Mode