bpo-27456: Simplify sock type checks (#4922)

Recent sock.type fix (see bug 32331) makes sock.type checks simpler
in asyncio.
diff --git a/Lib/asyncio/unix_events.py b/Lib/asyncio/unix_events.py
index 50d78c8..2ab6b15 100644
--- a/Lib/asyncio/unix_events.py
+++ b/Lib/asyncio/unix_events.py
@@ -222,7 +222,7 @@
             if sock is None:
                 raise ValueError('no path and sock were specified')
             if (sock.family != socket.AF_UNIX or
-                    not base_events._is_stream_socket(sock.type)):
+                    sock.type != socket.SOCK_STREAM):
                 raise ValueError(
                     f'A UNIX Domain Stream Socket was expected, got {sock!r}')
             sock.setblocking(False)
@@ -276,7 +276,7 @@
                     'path was not specified, and no sock specified')
 
             if (sock.family != socket.AF_UNIX or
-                    not base_events._is_stream_socket(sock.type)):
+                    sock.type != socket.SOCK_STREAM):
                 raise ValueError(
                     f'A UNIX Domain Stream Socket was expected, got {sock!r}')