drm/agpsupport: Replace "foo * bar" with "foo *bar"

This replaces all instances of foo * bar with foo *bar
in drm_agpsupport.c. This is so that it adheres to
standard C syntax for pointers.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/e092694c26e61fc6147e44851392a43b7a68c4f3.1505376068.git.meghana.madhyastha@gmail.com