doc: connectivity/networking/utils: minor fixes

Fixes bugs in USB and DSA group titles (networking) and a minor bug in
sys/utils.

Signed-off-by: Florian Grandel <[email protected]>

Author: fg-cfh

doc/_doxygen/groups.dox

@@ -36,14 +36,14 @@
 @brief Connectivity
 @defgroup connectivity Connectivity
 @{
+@}
 
 @brief USB
 @defgroup usb USB
+@ingroup connectivity
 @{
 @}
 
-@}
-
 @brief Utilities
 @defgroup utilities Utilities
 @{

include/zephyr/net/dsa.h

@@ -16,7 +16,7 @@
 
 /**
  * @brief DSA definitions and helpers
- * @defgroup DSA - Distributed Switch Architecture definitions and helpers
+ * @defgroup DSA Distributed Switch Architecture definitions and helpers
  * @ingroup networking
  * @{
  */