feat/efc: add API for read/erase/write flash #89

	name: Formatting
	on: [push, pull_request]

	env:
	CARGO_TERM_COLOR: always

	jobs:
	format:
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v2
	- name: Install Rust (thumbv7em)
	run: rustup show
	- run: \|
	set -xeu
	cargo fmt --package atsamx7x-hal -- --check
	for manifest in $(find ./boards -type f -iname Cargo.toml); do
	pushd $(dirname $manifest)
	cargo fmt -- --check
	popd
	done

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