package/x11r7/xserver_xorg-server: rename patches to the new convention

Patch 0003 will be extended to fix the blackfin build as well, therefore
it is renamed according to the fixed variable.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>