Changed the selection of the macro "DM_SELECT" from "(1, 256, 65536)" to "(1, 1, 65536)" in functions "calc_diff", "share_diff" and "set_target" in sgminer.c to fix "share is above target" message on quarkcoin kernel.

Changed the selection of the macro "DM_SELECT" from "(1, 256, 65536)" to "(1, 1, 65536)" in functions "calc_diff", "share_diff" and "set_target" in sgminer.c to fix "share is above target" message on quarkcoin kernel.