wigig_sensing: enforce data read in multiple of burst size

In case user space application requests for data size which is not a
multiple of the burst size and there is enough data in the drivers internal
buffer, a partial burst may be read by the application, which may cause
loss of burst boundary.

This patch fixes the above. In case the application supplies a buffer which
is smaller than the burst size, an error is returned to the application.

Change-Id: I5233476d99937dd1a13ceaec625588414a1dc04a
Signed-off-by: Gidon Studinski <gidons@codeaurora.org>