Revert "fbdev/radeon: use pci aperture helpers"

This reverts commit 6db53af1 which is
commit 9b539c4d upstream.

It breaks the Android ABI and can be brought back later in an abi-safe
way if needed.

Bug: 161946584
Change-Id: If14dd22c006f9d09857175a60c7f684409242515
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>