This patch adds the VSX Scalar Reciprocal Estimate Single Precision
(xsresp) instruction.

The existing VSX_RE macro is modified to support rounding of the
intermediate double precision result to single precision.
Signed-off-by: NTom Musta <tommusta@gmail.com>
Reviewed-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAlexander Graf <agraf@suse.de>