re-add frequencyin to 'timer_handler' after upstream merge

ports/atmel-samd/timer_handler.c

@@ -31,6 +31,7 @@
 
 #include "common-hal/pulseio/PulseOut.h"
 #include "shared-module/_pew/PewPew.h"
+#include "common-hal/frequencyio/FrequencyIn.h"
 
 static uint8_t tc_handler[TC_INST_NUM];
 
@@ -54,6 +55,9 @@ void shared_timer_handler(bool is_tc, uint8_t index) {
                 pewpew_interrupt_handler(index);
 #endif
                 break;
+            case TC_HANDLER_FREQUENCYIN:
+                frequencyin_interrupt_handler(index);
+                break;
             default:
                 break;
         }

ports/atmel-samd/timer_handler.h

@@ -29,6 +29,7 @@
 #define TC_HANDLER_NO_INTERRUPT 0x0
 #define TC_HANDLER_PULSEOUT 0x1
 #define TC_HANDLER_PEW 0x2
+#define TC_HANDLER_FREQUENCYIN 0x3
 
 void set_timer_handler(bool is_tc, uint8_t index, uint8_t timer_handler);
 void shared_timer_handler(bool is_tc, uint8_t index);