drivers: rpmh: disallow active state requests in solver mode.

SDM855 has separate TCS for SDE to send active mode or AMC requests.
When the solver mode is engaged, disallow the use of the RSC from Linux.

Change-Id: I9c696d04e409cde2485dce37e84f9208742acded
Signed-off-by: Lina Iyer <ilina@codeaurora.org>