ArmPlatformPkg: Remove orphaned Juno Makefile
ArmPlatformPkg: Remove orphaned Juno Makefile

The Juno .dsc and .fdf files were recently deleted (currently held
in OpenPlatformPkg), but a spurious Makefile for building using it
was left in place. Drop the Makefile to complete the cleanup.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Leif Lindholm <a613079f0455438b29e28a9c5b9eb3779a81a33a@linaro.org>
Reviewed-by: Ard Biesheuvel <66d3c5fdaeea7ff1f996ad04f2c45e08ab38e2f5@linaro.org>
Reviewed-by: Ryan Harkin <26c24e1ad4aed8194be813aa696391b1ea0548f2@linaro.org>

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