libdrm: update driver options

- add AMD GPU driver (available since 2.4.63)
- freedreno is no longer experimental (since 2.4.59)
- add NVIDIA Tegra driver (available since 2.4.59)
- update help texts (install vs. installs, change to complete
  sentences)

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>