interconnect: qcom: rpmh: fix registration race

The current interconnect provider registration interface is inherently
racy as nodes are not added until the after adding the provider. This
can specifically cause racing DT lookups to fail.

Switch to using the new API where the provider is not registered until
after it has been fully initialised.

Fixes: 976daac4

 ("interconnect: qcom: Consolidate interconnect RPMh support")
Cc: stable@vger.kernel.org      # 5.7
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Link: https://lore.kernel.org/r/20230306075651.2449-11-johan+linaro@kernel.org
Signed-off-by: Georgi Djakov <djakov@kernel.org>