plip: fix parport_register_device name parameter

Plip passes a string "name" that is allocated on stack to
parport_register_device.  parport_register_device holds the pointer to
"name" and when the registering function exits, it points nowhere.

On some machine, this bug causes bad names to appear in /proc, such as
/proc/sys/dev/parport/parport0/devices/T^/�X^/�, on others, the plip
proc node is completely missing.

The patch also fixes documentation to note this requirement.

Signed-off-by: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>