msm: kgsl: Remove io_fraction as it is no longer used

io_fraction was originally used as a way to influence the CPU
frequency governor.  Due to governor updates and timing changes
no targets use io_fraction now and there is no plan to do so in
the future.

Change-Id: Ib2739393d83a197d18d4446e6afcb889196f479b
Signed-off-by: Lucille Sylvester <lsylvest@codeaurora.org>