drivers: qcom: rpmh: avoid sending sleep/wake sets immediately

Fix the redundant call being made to send the sleep and wake requests
immediately to the controller.

As per the patch[1], the sleep and wake request votes are cached in rpmh
controller and sent during rpmh_flush(). These requests needs to be sent
only during entry of deeper system low power modes or suspend.

[1] https://patchwork.kernel.org/patch/10477533/

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Change-Id: Ieec3a2b46d6900ba74473b5f06519c7c2438f3e7
Signed-off-by: Raju P.L.S.S.S.N <rplsssn@codeaurora.org>
Reviewed-by: Lina Iyer <ilina@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>