stm32cube: u5: Add License file for the whole directory

The BSD 3-Clause LICENSE file provided in this commit matches
the LICENSE file referred to in files extracted from STM32CubeU5
package under directory stm32cube/stm32u5xx.

Additionally, fix license header in 2 files, which were likely
modified by the hal copy script.

Signed-off-by: Erwan Gouriou <[email protected]>
GitOrigin-RevId: 5c8275071ec1cf160bfe8c18bbd9330a7d714dc8
Change-Id: Ia0ac2139b3d5422264b41383c9c66724145d0fe8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/hal_stm32/+/3201001
Tested-by: Jack Rosenthal <[email protected]>
Reviewed-by: Jeremy Bettis <[email protected]>
Commit-Queue: Jack Rosenthal <[email protected]>
3 files changed