[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.

Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>