ARM: tegra: enable USB device mode and UMS on some boards

For each of Jetson TK1, Venice2, and Beaver:

- Enable the first USB controller in DT, and describe its configuration.

- Enable USB device/gadget support. This allows the user to type e.g.
  "ums 0 mmc 0" at the command-line to cause U-Boot to act a USB device
  implementing the USB Mass Storage protocol, and expose MMC device 0
  that way.

This allows a host PC to mount the Tegra device's MMC, partition it, and
install a filesystem on it.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
---
v3: Use assigned USB device ID rather than random made-up value.
v2: Add missing tegra-common-ums.h
dfu: fix some issues with reads/uploads

FIXME: This breaks filesystem DFU, since I've only implemented the
changes for raw device DFU.

DFU read support appears to rely upon dfu->read_medium() updating the
passed-by-reference len parameter to indicate the remaining size
available for reading.

dfu_read_medium_mmc() never does this, and the implementation of
dfu_read_medium_nand() will only work if called just once; it hard-codes
the value to the total size of the NAND device irrespective of read
offset.

I believe that overloading dfu->read_medium() is confusing. As such,
this patch introduces a new function dfu->get_medium_size() which can
be used to explicitly find out the medium size, and nothing else.
dfu_read() is modified to use this function to set the initial value for
dfu->r_left, rather than attempting to use the side-effects of
dfu->read_medium() for this purpose.

Due to this change, dfu_read() must initially set dfu->b_left to 0, since
no data has been read.

dfu_read_buffer_fill() must also be modified not to adjust dfu->r_left
when simply copying data from dfu->i_buf_start to the upload request
buffer. r_left represents the amount of data left to be read from HW.
That value is not affected by the memcpy(), but only by calls to
dfu->read_medium().

After this change, I can read from either a 4MB or 1.5MB chunk of a 4MB
eMMC boot partion with CONFIG_SYS_DFU_DATA_BUF_SIZE==1MB. Without this
change, attempting to do that would result in DFU read returning no data
at all due to r_left never being set.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
ARM: tegra: enable DFU too

Enable DFU protocol support (via the "dfu" command) on Tegra boards where
USB device/gadget mode is enabled.

This relies on a number of fixes to the ci_udc HW driver and DFU protocol
code.

Signed-off-by: Stephen Warren <swarren@nvidia.com>