huawei,tests: fix warnings with -Wdiscarded-qualifiers
CC huawei/tests/test_modem_helpers_huawei-test-modem-helpers-huawei.o
huawei/tests/test-modem-helpers-huawei.c:1176:41: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
1176 | { "^TIME: 14/08/05 04:00:21", TRUE, "2014-08-05T04:00:21" },
| ^~~~~~~~~~~~~~~~~~~~~
huawei/tests/test-modem-helpers-huawei.c:1177:43: error: initialization discards ‘const’ qualifier from pointer target type [-Werror=discarded-qualifiers]
1177 | { "^TIME: 2014/08/05 04:00:21", TRUE, "2014-08-05T04:00:21" },
| ^~~~~~~~~~~~~~~~~~~~~