unsigned req->data_len cannot be negative, and fix =-/-= typo
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
                break;
 
        case SMP_DISCOVER:
-               req->data_len =- 16;
-               if (req->data_len < 0) {
+               req->data_len -= 16;
+               if ((int)req->data_len < 0) {
                        req->data_len = 0;
                        error = -EINVAL;
                        goto out;
                break;
 
        case SMP_REPORT_PHY_SATA:
-               req->data_len =- 16;
-               if (req->data_len < 0) {
+               req->data_len -= 16;
+               if ((int)req->data_len < 0) {
                        req->data_len = 0;
                        error = -EINVAL;
                        goto out;
                break;
 
        case SMP_PHY_CONTROL:
-               req->data_len =- 44;
-               if (req->data_len < 0) {
+               req->data_len -= 44;
+               if ((int)req->data_len < 0) {
                        req->data_len = 0;
                        error = -EINVAL;
                        goto out;