Rather than creating new temporaries for constants, use the
ones created in disas_sparc_insn.  Remember the temps created
there so that they can be freed at the end of the function.

Profile data collected by TCG while booting sparc-test kernel:

-avg temps/TB    70.61 max=421
+avg temps/TB    62.75 max=66
Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>