cdc-wdm endianness fixes

* wMaxPacketSize is le16; copying it to a field of local structure and then
  using that field as host-endian (size of object to be allocated) is broken.
* bMaxPacketSize0 is 8-bit; feeding it to le16_to_cpu() is bogus and since the
  result is used as host-endian, it's not even misspelled cpu_to_le16().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>