parisc/stifb: Keep track of hardware path of graphics card

commit b046f984 upstream.

Keep the pa_path (hardware path) of the graphics card in sti_struct and use
this info to give more useful info which card is currently being used.

Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org   # v5.10+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>