Build: Merge tfm_partition_defs into tfm_config

CMake target tfm_partition_defs is merged into tfm_config. Same change
is also needed in tf-m-extras.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I3f30b5d3d5947d79afb8a7085f318a8ed5c64804
7 files changed