target-ppc: Eliminate set_fprf Argument From helper_compute_fprf

target-ppc: Eliminate set_fprf Argument From helper_compute_fprf

The set_fprf argument to the helper_compute_fprf helper function
is no longer necessary -- the helper is only invoked when FPSCR[FPRF]
is going to be set.

Eliminate the unnecessary argument from the function signature and
its corresponding implementation.  Change the return value of the
helper to "void".  Update the name of the local variable "ret" to
"fprf", which now makes more sense.

Signed-off-by: Tom Musta <tommusta@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>