base: Adding static constexpr keywords to log2i

Aligning to the rest of the file

Change-Id: If1e2d120f77843f8fdd4838fdb806a804236e58a
Signed-off-by: Giacomo Travaglini <giacomo.travaglini@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/42543
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/intmath.hh

@@ -155,7 +155,7 @@ roundDown(const T& val, const U& align)
  *
  * @ingroup api_base_utils
  */
-inline int
+static constexpr int
 log2i(int value)
 {
     assert(isPowerOf2(value) && value > 0);