drm/msm/dpu: Use indexed array initializer to prevent mismatches

While there's a comment pointing from dpu_intr_set to dpu_hw_intr_reg
and vice-versa, an array initializer using indices makes it so that the
indices between the enum and array cannot possibly get out of sync even
if they're accidentially ordered wrongly.  It is still useful to keep
the comment to be made aware where the register offset mapping resides
while looking at dpu_hw_intr_reg.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20220226194633.204501-1-marijn.suijten@somainline.org
Signed-off-by: Rob Clark <robdclark@chromium.org>