Remove dead code from radeonkms.

[markj]

Summary

This is effectively the closure of the ioctl handler table in
radeon_cp.c. That ioctl table is unused (we use the radeon_kms ioctl
table instead), so there is no way for any of the functions referenced
by the table to be called.

This was motivated by a report of an integer overflow vulnerability in
r600_cp_dispatch_texture() (the multiplication of tex->height and
tex->pitch, which are user-controlled). However, I believe the code
in question cannot get invoked.

Test Plan

I verified that radeonkms.ko still loads (i.e., no missing symbols).

Initially, my test was to simply comment out the radeon_ioctls[] table
and kldload, verifying that the ioctl handlers are indeed dead code.

[dumbbell]

Hi!

I suppose the int2float() function comes from one of the removed file, is that right? If yes, could you please add a comment indicating the initial source filename?

[markj]

• Add comment indicating the origin of int2float().

[markj]

In D18516#396189, @dumbbell wrote:

Hi!

I suppose the int2float() function comes from one of the removed file, is that right? If yes, could you please add a comment indicating the initial source filename?

Indeed, r600_blit.c. I added a comment.