icE1usb firmware: Detect A-bit in TS0; report via USB + LED

Scan over every odd E1 frame TS0 byte to check if the A-bit is set,
indicating a remote alarm.  If so, set yellow LED and report via the
error flags communicated to the host by USB interrupt transfer.

Change-Id: Ic4f57cf79bd32cf75f81ef3073cb8d4a2d1857d8
3 files changed