Revert "qsd8k: enable software vsync"

This reverts commit 1a2b83eab2236199d8c929b962ca3c6ef2ef2d48.
seems to break some apps:
ktrace
[  211.148864] mdp_wait: timeout waiting for mdp to complete 0x1
.....
[  211.189453] mdp_ppp_blit_and_wait: failed!
.....
[  211.317077] kernel BUG at drivers/video/msm/mdp_ppp.c:784!

Change-Id: Ib35a083e01a25814fd6d7a96c6be3ac9eecf4114