treewide: Move skip_atoi function to commonlib

BUG=none
TEST=Build and verify on Screebo
TEST=make unit-tests

```
$ make tests/commonlib/bsd/string-test
[==========] tests_commonlib_bsd_string-test(tests): Running 1 test(s).
[ RUN      ] test_skip_atoi
[       OK ] test_skip_atoi
[==========] tests_commonlib_bsd_string-test(tests): 1 test(s) run.
[  PASSED  ] 1 test(s).
```

Change-Id: Ifaaa80d0c696a625592ce301f9e3eefb2b4dcd98
Signed-off-by: Maximilian Brune <maximilian.brune@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/82910
Reviewed-by: Jakub Czapiga <czapiga@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>

tests/commonlib/bsd/string-test.c

@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <commonlib/bsd/string.h>
+#include <tests/test.h>
+
+/* Used to test skip_atoi */
+struct str_with_u_val_t {
+	char *str;
+	uint32_t value;
+	uint32_t offset;
+} str_with_u_val[] = {
+	{"42aa", 42, 2},
+	{"a", 0, 0},
+	{"0", 0, 1},
+	{"4a2", 4, 1},
+};
+
+static void test_skip_atoi(void **state)
+{
+	int i;
+	char *ptr, *copy;
+
+	for (i = 0; i < ARRAY_SIZE(str_with_u_val); i++) {
+		ptr = str_with_u_val[i].str;
+		copy = ptr;
+		assert_true(str_with_u_val[i].value == skip_atoi(&ptr));
+		assert_int_equal(str_with_u_val[i].offset, ptr - copy);
+	}
+}
+
+int main(void)
+{
+	const struct CMUnitTest tests[] = {
+		cmocka_unit_test(test_skip_atoi),
+	};
+
+	return cb_run_group_tests(tests, NULL, NULL);
+}