modules: cmsis_nn: Move Kconfig prompt out of CMSIS-DSP menu

The `CMSIS_NN` Kconfig previously depended on the `CMSIS_DSP` Kconfig,
and this placed the "CMSIS-NN Library Support" prompt under the "CMSIS-
DSP Library Support" menu (note that CMSIS-DSP is a menuconfig).

Since the CMSIS-NN library, although it requires the CMSIS-DSP library,
is not a subordinate component of the CMSIS-DSP library, remove its
dependency on `CMSIS_DSP` and make it select the Kconfig symbol
instead.

Signed-off-by: Stephanos Ioannidis <root@stephanos.io>
GitOrigin-RevId: 2c47a919afe214bd9a50e461d27749dd18f67cd6
Change-Id: I8e3d07e98bbce6bf7ff7d1f0d493b391307cd812
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/3628552
Tested-by: CopyBot Service Account <copybot.service@gmail.com>
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
1 file changed