netfront: Rename xennet_*_interrupt routines

It conflicts with 3.11 in the netfront event channel
handling routines.
netfront: Support for 3.11+ (up to 3.14)
bdgfn: a fix for free() of unused bdgreq
Merge pull request #1 from hwanju/my_test

bdgfn: a fix for free() of unused bdgreq