GDSCs were modeled as regulators till now. However,
moving forward, GDSCs will be treated as power domains.
Consequently, replace references to ‘regulators’ with
‘power domains’ for the sun GPU.
Change-Id: I607a511754d56728d5013004d0ae83544f873df6
Signed-off-by: Kamal Agrawal <quic_kamaagra@quicinc.com>