msm: kgsl: Use usleep_delay instead of cond_resched.

Use usleep_delay when waiting for CX votes to be removed,
usleep_delay will yield control to other RT threads.

Signed-off-by: Oleg Perelet <operelet@codeaurora.org>
Change-Id: Ia305dfe1e051a8fb603da595ad1e1cbcfc9f285c
Signed-off-by: George Shen <sqiao@codeaurora.org>