mips32, mips32_pracc_finish() queued only

In most of the cases there is no need to request execution,
the check for a new pracc access already does it.
Requesting execution if not needed makes execution slower and
code larger due the additional checks.
Reduce code in fasdata transfer function.
Call for execution when exiting debug.

Change-Id: I3b45f6d1f62da5fad3e3db84f82a9299b16e1bd9
Signed-off-by: Salvador Arroyo <sarroyofdez@yahoo.es>
Reviewed-on: http://openocd.zylin.com/4010


Tested-by: jenkins
Reviewed-by: Freddie Chopin <freddie.chopin@gmail.com>