common: remove coins.by_address_type because there are conflicts

Unfortunetly, there are coins with the same `address type` field. For
example ZClassic Coin uses the same one as Zcash.

src/apps/common/coins.py

@@ -15,13 +15,6 @@ def by_name(name):
     raise ValueError('Unknown coin name "%s"' % name)
 
 
-def by_address_type(address_type):
-    for c in COINS:
-        if c.address_type == address_type:
-            return c
-    raise ValueError("Unknown coin address type %d" % address_type)
-
-
 def by_slip44(slip44):
     for c in COINS:
         if c.slip44 == slip44:

tests/test_apps.common.coins.py

@@ -17,18 +17,14 @@ class TestCoins(unittest.TestCase):
         for s, n, a in ref:
             c1 = coins.by_shortcut(s)
             c2 = coins.by_name(n)
-            c3 = coins.by_address_type(a)
             self.assertEqual(c1, c2)
-            self.assertEqual(c1, c3)
-            self.assertEqual(c2, c3)
+            self.assertEqual(c1.address_type, a)
 
     def test_failure(self):
         with self.assertRaises(ValueError):
             coins.by_shortcut('XXX')
         with self.assertRaises(ValueError):
             coins.by_name('XXXXX')
-        with self.assertRaises(ValueError):
-            coins.by_address_type(1234)
 
 
 if __name__ == '__main__':