drm/msm/a6xx: fix crashdec section name typo

Backport note: maybe wait some time for the crashdec MR[1] to look for
both the old typo'd name and the corrected name to land in mesa 20.2

[1] https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6242



Fixes: 1707add8 ("drm/msm/a6xx: Add a6xx gpu state")
Signed-off-by: Rob Clark <robdclark@chromium.org>
Reviewed-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@chromium.org>