msm: ultrasound: reorganize kernel driver under misc drivers

Move ultrasound driver to comply with audio drivers location.

In addition, solve compilation errors when compiling with new
toolchain.

Change-Id: Ib8cd5e59111de826c0ed94d7facc51eef015ce52
Acked-by: Hadar Sivan <hsivan@qti.qualcomm.com>
Signed-off-by: Lior Barenboim <liorb@codeaurora.org>