drivers: lmh-dcvsh: Use FCAP scm call instead of DMAX

LMH-DCVSh driver right now achieves the software mitigation by using the
domain max scm call. But this could have some delays in clearing the
mitigation.

To avoid the delay, use the frequency cap scm call to place the
mitigation.

Change-Id: If357a57836fe0be13977a56a1f20567715908f25
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>