don't use SHIFTING test pattern. remove unused variable 'buf'

Author: jepler

examples/ov7670_displayio_gcm4_tftshield18.py

@@ -83,7 +83,7 @@ def deinit(self):
 pid = cam.product_id
 ver = cam.product_version
 print(f"Detected pid={pid:x} ver={ver:x}")
-cam.test_pattern = OV7670_TEST_PATTERN_SHIFTING_1
+# cam.test_pattern = OV7670_TEST_PATTERN_COLOR_BAR
 
 g = displayio.Group(scale=1)
 bitmap = displayio.Bitmap(160, 120, 65536)
@@ -95,7 +95,6 @@ def deinit(self):
 )
 g.append(tg)
 display.show(g)
-buf = memoryview(bitmap)
 
 t0 = time.monotonic_ns()
 display.auto_refresh = False