Do not let packages remove man pages, info pages and documentation

The cleanup of $(TARGET_DIR)/usr/share/man, $(TARGET_DIR)/usr/man,
$(TARGET_DIR)/usr/share/info, $(TARGET_DIR)/usr/info,
$(TARGET_DIR)/usr/share/doc and $(TARGET_DIR)/usr/doc is already done
globally in the main Makefile. Therefore, there's no need to handle
that on a per-package basis.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>