HID: hid-sensor-hub: fix report size

Most of the hid sensor field size is reported in report_size field
in the report descriptor. For rotation fusion sensor the quaternion
data is 16 byte field, the report size was set to 4 and report
count field is set to 4. So the total size is 16 bytes. But the current
driver has a bug and not taking account for report count field. This
causes user space to see only 4 bytes of data sent via IIO interface.
The number of bytes in a field needs to take account of report_count
field. Need to multiply report_size and report_count to get total
number of bytes.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>