drm/agpsupport: Move EXPORT_SYMBOL so that it immediately follows its function

EXPORT_SYMBOL(foo) should immediately follow its function/variable.
This coding style is preferred.
Found by checkpath.pl.

Signed-off-by: Meghana Madhyastha <meghana.madhyastha@gmail.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/0496f0e821082969ec7950ac35f1e6b6cedb22a6.1505376068.git.meghana.madhyastha@gmail.com