drm/msm: drop interrupt-names

Each GPU core only uses one interrupt so we don't to look up
an interrupt by name and thereby we don't need interrupt-names.

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