utf8_to_ucs2() function
utf8_to_ucs2 - Convert UTF-8 string to UCS-2 encoding @utf8_string: UTF-8 string (IN) @utf8_string_len: Length of utf8_string (IN) @ucs2_buffer: UCS-2 buffer (OUT) @ucs2_buffer_size: Length of UCS-2 buffer (IN) @ucs2_string_size: Number of 2-byte words in the resulting UCS-2 string Returns: 0 on success, -1 on failure