treewide: fix up files incorrectly marked executable

Joe Perches noted that we have a few source files that for some
inexplicable reason (read: I'm too lazy to even go look at the history)
are marked executable:

  drivers/gpu/drm/amd/amdgpu/vce_v4_0.c
  drivers/net/ethernet/cadence/macb_ptp.c

A simple git command line to show executable C/asm/header files is this:

    git ls-files -s '*.[chsS]' | grep '^100755'

and then you can fix them up with scripting by just feeding that output
into:

    | cut -f2 | xargs chmod -x

and commit it.

Which is exactly what this commit does.
Reported-by: Joe Perches <joe@perches.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>