pyfastservo adc: Fix find edge bug

- Fix: if frame changed at 31 tap delay, edge would not get detected

fast-servo/pyfastservo/adc.py

@@ -87,18 +87,15 @@ def perform_bitslip():
 
 def find_edge():
     prev_frame = read_frame()
-    transition = False
     for tap_delay in range(32):
         write_to_memory(ADC_DELAY_ADDR, tap_delay)
         current_frame = read_frame()
 
         print(f"Tap delay: {tap_delay}, Current frame: 0x{current_frame:02x}")
+        print(f"prev_frame: 0x{prev_frame:02x}")
 
         if current_frame != prev_frame:
-            if not transition:
-                transition = True
-            else:
-                final_delay = (tap_delay // 2) + 2
+            final_delay = ((tap_delay+1) // 2) + 2
             print(f"Edge detected; setting iDelay to: {final_delay}")
             write_to_memory(ADC_DELAY_ADDR, final_delay)
             return