clang-format: Add AfterCaseLabel option from clang-10

Seeing code format CI fails.

Caused by the recent move to clang-format-10:
https://gerrit.openbmc-project.xyz/c/openbmc/openbmc-build-scripts/+/32639

Added to the clang-format reference file here:
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/32696

Tested: None.
Change-Id: I268ab08d01d40963792d1df4499c65ce039b605b
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/.clang-format b/.clang-format
index dd27708..d17cf52 100644
--- a/.clang-format
+++ b/.clang-format
@@ -21,6 +21,7 @@
 BinPackArguments: true
 BinPackParameters: true
 BraceWrapping:
+  AfterCaseLabel: true
   AfterClass:      true
   AfterControlStatement: true
   AfterEnum:       true