linux-phytec-fsl

tty/vt/keyboard: use memdup_user to simplify code

use memdup_user rather than duplicating implementation.
found by coccinelle

Signed-off-by: Saurabh Sengar <saurabh.truth@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>