msm: cpr-regulator: change CPR_CORNER to CPR_FUSE_CORNER

New changes introduce virtual corner concept as opposed to cpr_corner.
Cpr corners in existing code are all cpr fuse corners. Hence change them
to distinguish cpr fuse corner from cpr virtual corner.

Change-Id: I086b29cadb23edfdff583f21f29efad4b35be5e1
Signed-off-by: Ke Liu <keliu@codeaurora.org>