msm: smd: fix spelling mistake in copper platform data comment

The spelling mistake makes the top level interrupt line name documentation
inaccurate.  Correct the mistake to make the documentation accurate for
future reference.

Change-Id: I9aa455f131bb99e49c6d5cda8e1da0ac06df15e8
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>