On Huawei ME936, the hex numbers in the response to AT^DHCP contain the 0x prefix, e.g.
AT^DHCP?
^DHCP: 0xda7d0e0a,0xff000000,0xdb7d0e0a,0xdb7d0e0a,0x01261aac,0x00000000,100000000,50000000
This patch updates mm_huawei_parse_dhcp_response() to handle the
optional 0x prefix.