test/py: Drop u_boot_ prefix on test files

We know this is U-Boot so the prefix serves no purpose other than to
make things longer and harder to read. Drop it and rename the files.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # test_android / test_dfu
diff --git a/test/py/tests/test_mmc.py b/test/py/tests/test_mmc.py
index 4ecd999..4916dcd 100644
--- a/test/py/tests/test_mmc.py
+++ b/test/py/tests/test_mmc.py
@@ -4,7 +4,7 @@
 import pytest
 import random
 import re
-import u_boot_utils
+import utils
 
 """
 Note: This test doesn't rely on boardenv_* configuration values but it can
@@ -290,7 +290,7 @@
                 for y in mmc_modes:
                     ubman.run_command('mmc dev %d %d %d' % x, part, y)
                     part_detect = 1
-                    addr = u_boot_utils.find_ram_base(ubman)
+                    addr = utils.find_ram_base(ubman)
                     devices[x]['addr_%d' % part] = addr
                     size = random.randint(4, 1 * 1024 * 1024)
                     devices[x]['size_%d' % part] = size
@@ -394,7 +394,7 @@
                 for y in mmc_modes:
                     ubman.run_command('mmc dev %d %d %d' % x, part, y)
                     part_detect = 1
-                    addr = u_boot_utils.find_ram_base(ubman)
+                    addr = utils.find_ram_base(ubman)
                     devices[x]['addr_%d' % part] = addr
                     size = random.randint(4, 1 * 1024 * 1024)
                     devices[x]['size_%d' % part] = size
@@ -658,7 +658,7 @@
                 for y in mmc_modes:
                     ubman.run_command('mmc dev %d %d %d' % x, part, y)
                     part_detect = 1
-                    addr = u_boot_utils.find_ram_base(ubman)
+                    addr = utils.find_ram_base(ubman)
                     count_f = 0
                     addr_l = []
                     size_l = []