media: dvb-usb: Fix memory leak at error in dvb_usb_device_init()

media: dvb-usb: Fix memory leak at error in dvb_usb_device_init()

dvb_usb_device_init() allocates a dvb_usb_device object, but it
doesn't release the object by itself even at errors.  The object is
released in the callee side (dvb_usb_init()) in some error cases via
dvb_usb_exit() call, but it also missed the object free in other error
paths.  And, the caller (it's only dvb_usb_device_init()) doesn't seem
caring the resource management as well, hence those memories are
leaked.

This patch assures releasing the memory at the error path in
dvb_usb_device_init().  Now dvb_usb_init() frees the resources it
allocated but leaves the passed dvb_usb_device object intact.  In
turn, the dvb_usb_device object is released in dvb_usb_device_init()
instead.
We could use dvb_usb_exit() function for releasing everything in the
callee (as it was used for some error cases in the original code), but
releasing the passed object in the callee is non-intuitive and
error-prone.  So I took this approach (which is more standard in Linus
kernel code) although it ended with a bit more open codes.

Along with the change, the patch makes sure that USB intfdata is reset
and don't return the bogus pointer to the caller of
dvb_usb_device_init() at the error path, too.

Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>