Remove stm32.

stm32 developemnt continues in the `stm32-neo` branch for now.

embassy-stm32-examples/.cargo/config.toml

@@ -1,28 +0,0 @@
-[target.'cfg(all(target_arch = "arm", target_os = "none"))']
-runner = "probe-run --chip STM32F401CCUx"
-
-rustflags = [
-  # LLD (shipped with the Rust toolchain) is used as the default linker
-  "-C", "link-arg=--nmagic",
-  "-C", "link-arg=-Tlink.x",
-  "-C", "link-arg=-Tdefmt.x",
-
-  # if you run into problems with LLD switch to the GNU linker by commenting out
-  # this line
-  # "-C", "linker=arm-none-eabi-ld",
-
-  # if you need to link to pre-compiled C libraries provided by a C toolchain
-  # use GCC as the linker by commenting out both lines above and then
-  # uncommenting the three lines below
-  # "-C", "linker=arm-none-eabi-gcc",
-  # "-C", "link-arg=-Wl,-Tlink.x",
-  # "-C", "link-arg=-nostartfiles",
-
-  # Code-size optimizations.
-  "-Z", "trap-unreachable=no",
-  "-C", "inline-threshold=5",
-  "-C", "no-vectorize-loops",
-]
-
-[build]
-target = "thumbv7em-none-eabi"