hw/arm/spitz: Detabify

The spitz board has been around a long time, and still has a fair number
of hard-coded tab characters in it. We're about to do some work on
this source file, so start out by expanding out the tabs.

This commit is a pure whitespace only change.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20200628142429.17111-2-peter.maydell@linaro.org