msm: clock-8092: Modify sibling flag of vpu_vdp_xin_clk

vpu_vdp_xin_clk is the only branch from vpu_vdp_xin_clk_src.
Allow vpu_vdp_xin_clk to set rate on source.

Change-Id: I1fcc20bed6b3bc84da9f53f31468e69bf8c799c0
Signed-off-by: Tirupathi Reddy <tirupath@codeaurora.org>