defconfigs: use BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_

defconfigs: use BR2_PACKAGE_HOST_UBOOT_TOOLS_ENVIMAGE_

For defconfigs that create a boot envimage, add the host package
uboot-tools and update the script variable names.

Add BR2_PACKAGE_HOST_UBOOT_TOOLS=y just before the existing
BR2_TARGET_UBOOT_ENVIMAGE option. Note that for the defconfigs that are
not manually formatted (i.e. just the result of 'make savedefconfig'),
this puts them in the wrong place. However, it's easier this way, and
it's more consistent in general to have the definition of the envimage
close to BR2_TARGET_UBOOT itself.

Related to 78559d699ae4b5c22ae77cfb7994560e0267be96

Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Matthew Weber <matthew.weber@rockwellcollins.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>