drm/panfrost: default_supplies[] can be static

Fixes: 3e1399bc

 ("drm/panfrost: Add support for multiple regulators")
Signed-off-by: kbuild test robot <lkp@intel.com>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200227014100.GA61938@e50d7db646c3