kunit: kunit_config: Fix parsing of CONFIG options with space

Commit 8b59cd81 ("kbuild: ensure full rebuild when the compiler is
updated") introduced a new CONFIG option CONFIG_CC_VERSION_TEXT. On my
system, this is set to "gcc (GCC) 10.1.0" which breaks KUnit config
parsing which did not like the spaces in the string.

Fix this by updating the regex to allow strings containing spaces.

Fixes: 8b59cd81 ("kbuild: ensure full rebuild when the compiler is updated")
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>