msm: ultrasound: fix input device memory leak

Error handling in touch screen input device creation did not
free the allocated input device, creating a possible memory leak.

This change adds a call to input_device_free() to correct this.

Change-Id: I564d8deebf30d01c95f8f43de01be2bff0ddf75d
Signed-off-by: Lior Barenboim <liorb@codeaurora.org>