drm/msm: drop _clk suffix from clk names

Suggested by Rob Herring.  We still support the old names for
compatibility with downstream android dt files.

Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Acked-by: Rob Herring <robh@kernel.org>