kunit: Create default config in '--build_dir'

If both '--build_dir' and '--defconfig' are given, the handling of
'--defconfig' ignores '--build_dir' option.  This commit modifies the
behavior to respect '--build_dir' option.

Reported-by: Brendan Higgins <brendanhiggins@google.com>
Suggested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
diff --git a/tools/testing/kunit/kunit_kernel.py b/tools/testing/kunit/kunit_kernel.py
index bf38768..c04a12e 100644
--- a/tools/testing/kunit/kunit_kernel.py
+++ b/tools/testing/kunit/kunit_kernel.py
@@ -14,7 +14,7 @@
 import kunit_config
 
 KCONFIG_PATH = '.config'
-KUNITCONFIG_PATH = 'kunitconfig'
+kunitconfig_path = 'kunitconfig'
 
 class ConfigError(Exception):
 	"""Represents an error trying to configure the Linux kernel."""
@@ -82,7 +82,7 @@
 
 	def __init__(self):
 		self._kconfig = kunit_config.Kconfig()
-		self._kconfig.read_from_file(KUNITCONFIG_PATH)
+		self._kconfig.read_from_file(kunitconfig_path)
 		self._ops = LinuxSourceTreeOperations()
 
 	def clean(self):