boards: scobc_a1: Rename board name to scobc-a1

In the EM (Engineering Model), the board was referred to as
"Space Cubics Module 1". Starting with the FM (Flight Model) release,
we are officially renaming it to:

  `SC-OBC Module A1`

Accordingly, the board name is updated from `scobc_module1` to
`scobc_a1`.

Signed-off-by: Takuya Sasaki <takuya.sasaki@spacecubics.com>