stdio: remove useless strncpy

The name is already copied when we memcpy() the whole structure.

This is because struct stdio_dev has this field:

	char	name[16];		/* Device name				*/

So the data is inline, rather than being a pointer.

Signed-off-by: Vincent Palatin <vpalatin@chromium.org>

Signed-off-by: Simon Glass <sjg@chromium.org>