drivers: thermal: Use FCAP scm call instead of DMAX in KTM

KTM 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: Manaf Meethalavalappu Pallikunhi <manafm@codeaurora.org>