target-utils: added 10 ms delay at the end of abb_power_off() The deosmification of the ABB access code (replacement of osmo_delay_ms() bogus delays with correctly-timed ones, which are significantly shorter) had one annoying side effect: when executing the poweroff command from any of the programs, one last '=' prompt character was being sent (and received by the x86 host) as the Calypso board powers off. With delays being shorter now, the abb_power_off() function was returning and the standalone program's main loop was printing its prompt before the Iota chip fully executed the switch-off sequence! I thought about inserting an endless tight loop at the end of the abb_power_off() function, but the implemented solution of a 10 ms delay is a little nicer IMO because if the DEVOFF operation doesn't happen for some reason in a manual hacking scenario, there won't be an artificial blocker in the form of a tight loop keeping us from further poking around.

The library built in this directory is a host side library, not for the target.
This library implements some functions for handling packet exchanges with GPF,
and it will be linked by some of the programs in the rvinterf suite.

It needs to be noted that the RVTMUX channel belonging to GPF was named
RVT_L23_HEADER by TI, and as a result, I thought that these packets related
specifically to the higher layers of the protocol stack.  But now we know that
hierarchically speaking, GPF sits *below* L1, not above, and GPF packets should
not be automatically associated with G23.  This realization was made fairly
late, thus "g23" appears in a bunch of function names, and in the name of this
library.