msm: ADSPRPC: Change driver initialization to late_initcall

The driver depends on MSM IOMMU subsystem driver to be initialized
first to get the domain information. Move the initialization phase
of the driver to late_initcall so that the dependent drivers get
initialized first.

Change-Id: Id9524f09f21110aa7539434e9febdd2b84361f9d
Acked-by: Sathish Ambley <sambley@qti.qualcomm.com>
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org>