boards: scobc_a1: Fix YAMLLint error

Fixes the YAMLLint error as below:

   YAMLLint (indentation):wrong indentation: expected 4 but found 2
   File:boards/sc/scobc_a1/board.yml
   Line:12
   Column:3

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

boards/sc/scobc_a1/board.yml

@@ -9,4 +9,4 @@ board:
       - name: 1.0.0
       - name: 2.0.0
   socs:
-  - name: designstart_fpga_cortex_m3
+    - name: designstart_fpga_cortex_m3