hw/arm: Remove deprecated akita, borzoi, spitz, terrier, tosa boards

hw/arm: Remove deprecated akita, borzoi, spitz, terrier, tosa boards

The Sharp XScale-based PDA board models akita, borzoi, spitz,
terrier, and tosa were all deprecated in 9.0, so our deprecation
cycle permits removing them for the 9.2 release.

Remove the source files for the board models themselves, and their
documentation. There were no tests for these boards.

We will move the text describing the dropped boards from
deprecated.rst to removed-features.rst when we've cleaned up all the
boards it lists.  Device models used only by removed board models
will be removed in separate commits.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20240903160751.4100218-2-peter.maydell@linaro.org