misc: c2port: core: Make copying name from userspace more secure

misc: c2port: core: Make copying name from userspace more secure

Currently the 'c2dev' device data is not initialised when it's
allocated.  There maybe an issue when using strncpy() to populate the
'name' attribute since a NUL terminator may not be provided in all
use-cases.  To prevent such a failing, let's ensure the 'c2dev'
device data area is fully zeroed out on allocation.

Cc: Rodolfo Giometti <giometti@enneenne.com>
Cc: "Eurotech S.p.A" <info@eurotech.it>
Cc: David Laight <David.Laight@aculab.com>
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201102142001.560490-1-lee.jones@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>