drivers: ufs: fix buffer overflow in sprintf

drivers/scsi/ufs/ufshcd.c:7588:3: error: 'sprintf' will always overflow; destination buffer has size 16, but format string expands to at le
ast 17 [-Werror,-Wfortify-source]
                sprintf(buf, "U%dH%dL%dX%dQ%dR%dW%dF%d",
                ^

Change-Id: Ic03043dc5df59faf7f19a03deb2fb2d558910db0