Instead of every "simple" target having their own duplicate file with
all the section mappings, just provide a single, simple,
"cortex-m-generic.ld" that works with our startup code and any simple
rom/ram system. This also drops the pointless copying of files all over
the place. Using -L flags properly is sufficient, and the standard file
is now in the root of the library already.
The filename has always been wrong, "6" is a temperature grade, but f405 and
f407 are in the same datasheet, and all have the 64k CCM. Add it to the linker
script.
