Merged in masayuki2009/nuttx.nuttx/stm32f4discovery_rndis (pull request #533)

RNDIS support on STM32F4Discovery

* stm32f4discovery: Add stm32_netinit.c to avoid a compilation error

* stm32f4discovery: Add rndis initialization in stm32_bringup.c

    NOTE: MAC address for the host side starts 0xaa.  This assignment
    scheme should be fixed later.

* stm32f4discovery: Add rndis configuration

    NOTE: STM32F4Discovery + DM-STF4BB

* drivers/usbdev/rndis.c: Fix some issues in rndis.c

    Introduce rndis_transmit() and change rndis_rxdispatch() to avoid
    packet corruption. Introduce max packet size for dual speed which
    is mainly used for high speed mode. Fix adjusting MTU warning
    on Linux host. Fix data corruption if a packet size excceds MTU.

    NOTE: Max packet size is not configured dynamically. This should
    be fixed in the future version.

* stm32f4discovery: Modify #ifdef condition for rndis in stm32_bringup()

* drivers/usbdev/rndis.c: Change HPWORK to ETHWORK

* drivers/usbdev/rndis.c: Merge the commit 07b98ccb

    Previous commit b09365784a was based on old rndis.c thus resulted
    in reverting the commit 07b98ccb. This change merges the commit.

    NOTE: In the commit 07b98ccb

, max packet size of bulkout was
    assumed to be 64. In this commit, priv->epbulkout->maxpacket is
    used instead.

Approved-by: Gregory Nutt <gnutt@nuttx.org>