msm: camera: Remove total steps restriction for continuous auto focus

The autofocus function fails under certain test condition
due to restriction on the total number of steps available
for moving the lens. The issue is seen only with piezo
type of actuators. This fix ensures the piezo actuator can
move upto its mechanical limits.

Change-Id: Ic718b4a55016a1cc4a3aecea332e98ba326226c5
Signed-off-by: Rajakumar Govindaram <rajakuma@codeaurora.org>
CRs-Fixed: 332887