[media] fimc-lite: Initialize 'step' field in fimc_lite_ctrl structure
v4l2_ctrl_new() uses check_range() for control range checking.
This function expects 'step' value for V4L2_CTRL_TYPE_BOOLEAN type control.
If 'step' value doesn't match to '1', it returns -ERANGE error.
This patch adds the default .step value to 1.