The previous implementation of copy_from_pm assumed the destination buffer
was aligned on a 16-bit boundary. On M0/M0+ cores (stm32F0*, stm32L0*)
this causes a hard fault.
This implementation is from Kuldeep Dhaka's tree; it does a 16-bit copy
only if the destination buffer is aligned, otherwise a bytewise copy.
Fixes GH issues #401, #461
Based on previous work, add a new driver for the v2 usb peripheral found on
stm32f0 and l0 devices.
Correspondingly, add a usb gadget zero test suite for the f0. L0 device level
code isn't yet ready, but will add the test case when it moves in.
Work by Frantisek Burian, Kuldeep
Singh Dhaka, Robin Kreis, fenugrec and zyp on irc, and all those forgotten.
