Add udev rules and scripts for demo platform configuration

Add recipes for udev rules and associated scripts provided by
Jan-Simon Möller to:
1) Support USB attached I2C devices for RTC and HVAC LED support.
   The RTC support loads and configures the required rtc-ds1307
   driver, and sets the time from the RTC clock.  The HVAC LED
   support configures the LED device names for use by the HVAC
   binding.
2) Detect Fiberdyne MOST attached amp and install the required 4A
   HAL.

The new demo-i2c-udev-conf and demo-most-udev-conf recipes are
added to DEMO_PLATFORM_CONF variable in packagegroup-agl-demo-platform
to have them added to the agl-demo-platform image.  Since they use
udev rules to detect the corresponding hardware, this should be safe
for all platforms.

Change-Id: I9dc78b8e63418079d14e1d1e2a832840a0c97ea8
Signed-off-by: Scott Murray <scott.murray@konsulko.com>