msm: vidc: Handoff regulators after firmware loading is complete

Regulator handoff causes the GDSC to turn off momentarily and resets
internal registers. As a result, TZ is unable to program secure
registers during Secure PIL load fails. Moving the handoff after
PIL load allows proper secure register programming and enables
secure sessions.

CRs-Fixed: 2450296
Change-Id: I32c7bf8726b51fdfa73b40819e8fdccdbbc0abe3
Signed-off-by: Chinmay Sawarkar <chinmays@codeaurora.org>