USB CDC NCM host driver

The patch provides USB CDC NCM host driver support in the Linux Kernel.

Changes:
drivers/net/usb/cdc_ncm.c:
- initial submission of the CDC NCM host driver;
- verified on Intel 32/64 bit, Intel Atom, ST-Ericsson U8500 (ARM)
- throughput measured over 100 Mbits duplex;
- driver supports 16-bit NTB format only, but it is more than enough for
  transfers up to 64K;
- driver can handle up to 32 datagrams in received NTB;
- timer is used to collect several packets in Tx direction

drivers/net/usb/Kconfig:
- a new entry to compile CDC NCM host driver
drivers/net/usb/Makefile:
- a new entry to compile CDC NCM host driver

Signed-off-by: Alexey Orishko <alexey.orishko@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>