Revert "usb: gadget: f_ecm: Refactor bind path to use __free()"

This reverts commit 070f341d which is
commit 42988380 upstream.

It breaks the Android kernel abi and can be brought back in the future
in an abi-safe way if it is really needed.

Bug: 161946584
Change-Id: I0d63d61e8f584173e2c29a046b29e4fca690cfa7
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>