drm/msm: Support 64 bit iova in RD_CMDSTREAM_ADDR

Output the upper 32 bits of a 64 bit iova in the RD_CMDSTREAM_ADDR
section while maintaining backwards compatibility for tools that
only understand 32 bit iovas.

Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>