clk: qcom: clk-rcg2: Allow DFS clients to scale the RCG while its enabled

Currently, the clock driver does not allow for clock clients
to call set_rate() on the DFS enabled clocks while the RCG
is ON. This is to prevent any unvoting on resources that the
RCG might still be using. However, this new requirement could
mean that clients need to redesign their call flow around the
fact that DFS has been enabled/not.
To prevent any such churn on the client side, remove these
restrictions and leave it to the client to correctly call
the APIs.

Change-Id: Id2d87c4f9c7aed89c56084c72f8b1d2a16fe9189
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>
Signed-off-by: Taniya Das <tdas@codeaurora.org>