style(clang-format): add Clang-Format configuration

Add a configuration for the Clang-Format C and C++ code style formatter.
This is based on the Clang-Format used by the Linux kernel with some
minor modifications:

- the for-each macros reflect what we have available in TF-A
- sorting of include files roughly follows our existing strategy

Change-Id: I8366c935a146175c14249e084a8328bbba05c7c8
Signed-off-by: Chris Kay <chris.kay@arm.com>
2 files changed