trivial: Fix compiler warnings

- Add missing return statements
- Add missing const modifiers
- Initialize variables correctly
- Remove unused variables
- Correct incorrect type definitions
- Use correct printf format string types

trivial: Fixed the order of \r and \n

SerialServer: Shared memory putchar interface

A shared memory interface `batch` for putchar that allows clients
to send more than one character to SerialServer at once.

SerialServer: Don't use badge values as client ids

The SerialServer expects its client ids to start from 0 and be
contiguous, therefore it shouldn't use badge values for this as a badge
value of 0 for a client_id is used to represent an unbadged client and
shouldn't exist.

SerialServer: Don't always init virtqueues

When no virtqueues are connected, don't bother trying to initialise them
as this generates spurious error output and is often misleading.

serial: fix output colours

Change-Id: Iee628975e077aef68c5975c5fb70276341badfff

SerialServer: Combine IRQ ops and IO ops init

Now that an IRQ ops structure can be initialised by calling
camkes_io_ops, we combine and condense the calls in SerialServer.

SerialServer: Update non-plat code for IRQ iface

This commit updates the non-platform specific code to conform to the new
IRQ interface.

trivial: astyle SerialServer to meet style

SerialServer: Update serial.c for code changes

This commit follows from the previous 2 commits in which the IRQ
handling code was updated and an additional platform initialisation
function was added.

SerialServer: Update serial.c to use new plat code

This commit updates the main SerialServer source file to call the new
platform specific IRQ code.

SerialServer: Updated style

SerialServer: Added support for virtqueues

Extented the implementation of the SerialServer to support
virtqueues. This allows the serial server to faciliate bulk data
transfers to and from serial. This SerialServer has two
virtqueues, for a TX and RX channel.

SerialServer: Refactored SerialServer source

Split up the serial server source code into general and platform
specific code. In doing so the PC99 specific code has been moved
to a platform source folder 'src/plat/pc99'. This opens the way
for using the SerialServer on different machines/platforms
(provided a platform/machine backend is implemented)

SerialServer: use ansi.h

Remove duplication of definitions, also easier to extend

SerialServer: mark symbols as weak

This is so that the serial server functions if certain interfaces are
not connected

Fix race condition in serial server

Server would crash if characters were entered during preinit.

Move components from camkes-vm project

These x86 components can be reused in other projects