codespell: skip amdgpu kernel headers

These header files are copied directly from the Linux kernel and contain
typos. We skip these files in codespell to simplify maintenance.

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

Author: rst0git

.codespellrc

@@ -1,3 +1,3 @@
 [codespell]
-skip = ./.git,./test/pki,./tags
+skip = ./.git,./test/pki,./tags,./plugins/amdgpu/amdgpu_drm.h,./plugins/amdgpu/drm.h,./plugins/amdgpu/drm_mode.h
 ignore-words-list = creat,fpr,fle,ue,bord,parms,nd,te,testng,inh,wronly,renderd,bui,clen,sems