emccanon.cc: fix getStraightAcceleration() bug
emccanon.cc: fix getStraightAcceleration() bug

The "acc" calculation for both (canon.cartesian_move && canon.angular_move)
is buggy. Roll back to the one from joints_axes_3.

araisrobo/linuxcnc,araisrobo/linuxcnc,araisrobo/linuxcnc,araisrobo/linuxcnc,araisrobo/linuxcnc