fix(docker): correct conditional check for DISABLE_PERIPHERAL_API

Fix the syntax error in the shell script where the comparison was
incorrectly structured, and remove the redundant passing of the
variable value to the flag.

docker-entrypoint.sh

@@ -128,8 +128,8 @@ if [ -n "${PERIPHERAL_VOLUME_STEP}" ]; then
   EXTRA_ARGS+=( "--peripheral-volume-step" "$PERIPHERAL_VOLUME_STEP" )
 fi
 
-if [ -n "$DISABLE_PERIPHERAL_API" = "1" ]; then
-  EXTRA_ARGS+=( "--disable-peripheral-api" "$DISABLE_PERIPHERAL_API" )
+if [ "$DISABLE_PERIPHERAL_API" = "1" ]; then
+  EXTRA_ARGS+=( "--disable-peripheral-api" )
 fi
 
 if [ "$ENABLE_OUTPUT_ONLY" = "1" ]; then