sensor: fix BMI160 sensor hang issue

Fix several issues which are causing the BMI160 app hang.

For SPI duplex transfer, QMSI only supports equal length.
For SPI freq, divider is used. Actual freq is no longer used.

Jira: ZEP-461

Change-Id: I1a1bcc12c6514c3797686dfdad1ce1b852f7dc78
Signed-off-by: Baohong Liu <baohong.liu@intel.com>