Fix crash on boot

There is a race condition where the sysfs-vsync thread accesses a value
(in particular a function ptr) that may not have been set yet as this
is done externally.
Also a typo fix

Change-Id: I21d7024c793ab3b8d833c3a8305110128237ba36
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_hardware_ti_omap4xxx into kk44