images/*-sdk: remove debug-tweaks from IMAGE_FEATURES
There's no need for the SDK images to explicitly list debug-tweaks, this
is typically added via EXTRA_IMAGE_FEATURES when needed.
(From OE-Core rev: f23eae893837f91dd9dfe027a2209c34c6845bbf)
Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>