drm/radeon: Replace one-element array with flexible-array member

[ Upstream commit c81c5bd5cf2f428867e0bcfcccd4e4d2f8c68f51 ]

One-element arrays are deprecated, and we are replacing them with
flexible array members instead. So, replace one-element array with
flexible-array member in struct _ATOM_FAKE_EDID_PATCH_RECORD and
refactor the rest of the code accordingly.

It's worth mentioning that doing a build before/after this patch results
in no binary output differences.

This helps with the ongoing efforts to tighten the FORTIFY_SOURCE
routines on memcpy() and help us make progress towards globally
enabling -fstrict-flex-arrays=3 [1].

Link: https://github.com/KSPP/linux/issues/79
Link: https://github.com/KSPP/linux/issues/239
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101836

 [1]

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Paulo Miguel Almeida <paulo.miguel.almeida.rodenas@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Stable-dep-of: 17c6baff3d5f ("drm/radeon: properly handle vbios fake edid sizing")
Signed-off-by: Sasha Levin <sashal@kernel.org>