drm/qxl: Remove trailing whitespace

Remove extra tab and space to clean the checkpath.pl error.

ERROR: trailing whitespace
Signed-off-by: Shayenne da Luz Moura <shayenneluzmoura@gmail.com>
Link: http://patchwork.freedesktop.org/patch/msgid/fb0e2237bc505c855a0a842c081a39d524c571dc.1540579956.git.shayenneluzmoura@gmail.comSigned-off-by: Gerd Hoffmann <kraxel@redhat.com>