fixed PS/2 keyboard converter config

When using the PS/2 interrupt implementation, the DATA pin should be
PD0 as the documentation (README.md) states.

converter/ps2_usb/config.h

@@ -69,7 +69,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #define PS2_DATA_PORT   PORTD
 #define PS2_DATA_PIN    PIND
 #define PS2_DATA_DDR    DDRD
-#define PS2_DATA_BIT    2
+#define PS2_DATA_BIT    0
 #define PS2_INT_INIT()  do {    \
     EICRA |= ((1<<ISC11) |      \
               (0<<ISC10));      \