Turned on g_serial and DHCP in menuconfig

- Turned on USB_G_SERIAL (as module, =m), in:

  Device Drivers -> USB support -> USB Gadget Support -> USB Gadget Drivers ->
   Serial Gadget (with CDC ACM and CDC OBEX support)

- Turned on IP_PNP_DHCP, in:

  Networking support -> Networking options -> TCP/IP networking -> IP: kernel
   level autoconfiguration -> IP: DHCP support
Changed the I2C bus speed from 100 kHz to 400 kHz
Updated USB g_serial vendor ID and product ID

- Changed vendor ID from 0x0525 (NetChip) to 0x116D (Filmetrics)
- Changed product ID from 0xA4A7 to 0x0080
- Changed name from "Gadget Serial v2.4" to "FI Instrument"