[VPlan] Silence gcc Wparentheses warning [NFC]

Without the fix gcc warns about
../lib/Transforms/Vectorize/VPlanTransforms.cpp:968:42: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  968 |          UseActiveLaneMaskForControlFlow &&
      |          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~
  969 |              "DataAndControlFlowWithoutRuntimeCheck implies "
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  970 |              "UseActiveLaneMaskForControlFlow");
      |              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~