chore(SpecialFunctions/Log): fix naming typo (leanprover-community#41773)

This lemma used to be named `EReal.ENNReal.rpow_eq_exp_mul_log` which I presume was accidental and the name was intended to be `ENNReal.rpow_eq_exp_mul_log`, and so this PR renames accordingly.

Author: b-mehta

Mathlib/Analysis/SpecialFunctions/Log/ENNRealLogExp.lean

@@ -63,13 +63,17 @@ lemma exp_nmul (x : EReal) (n : ℕ) : exp (n * x) = (exp x) ^ n := by
 lemma exp_mul (x : EReal) (y : ℝ) : exp (x * y) = (exp x) ^ y := by
   rw [← log_eq_iff, log_rpow, log_exp, log_exp, mul_comm]
 
-lemma ENNReal.rpow_eq_exp_mul_log (x : ℝ≥0∞) (y : ℝ) : x ^ y = exp (y * log x) := by
-  rw [mul_comm, EReal.exp_mul, exp_log]
-
 end EReal
 end Exp
 
 namespace ENNReal
+
+lemma rpow_eq_exp_mul_log (x : ℝ≥0∞) (y : ℝ) : x ^ y = exp (y * log x) := by
+  rw [← log_rpow, exp_log]
+
+@[deprecated (since := "2026-07-15")] alias _root_.EReal.ENNReal.rpow_eq_exp_mul_log :=
+  rpow_eq_exp_mul_log
+
 section OrderIso
 
 set_option backward.isDefEq.respectTransparency false in