meta-agl-bsp: More CES 2017 demo hardware support for TI Vayu

Tweaked the rtl_sdr.cfg fragment for linux-ti-staging to add CONFIG_I2C_MUX,
as it is required by the RTL28xx driver Kconfig in newer kernels.  As well,
added another fragment to linux-ti-staging to enable USB Bluetooth HCI
devices so that USB Bluetooth adapters will work on Vayu.

Change-Id: Ifd40f25e2159066fea4707a7915ba9b6dee52e0c
Signed-off-by: Scott Murray <scott.murray@konsulko.com>