ARM: dts: msm: Add node clock for ocmem venus on msm8994

On msm8994 venus core has an additional clock that needs to
be aggregated in addition to the ocmem core clk.

Change-Id: I8883fce6d05fb13d4e46563132eff20d4b7cd0c1
Signed-off-by: Girish Mahadevan <girishm@codeaurora.org>