[sram, dv] Fix a regression failure

In env_cfg, `initialize` is invoked before randomize
Moved clk_freqs_mhz override to `post_randomize`

Signed-off-by: Weicai Yang <weicai@google.com>

hw/ip/sram_ctrl/dv/env/sram_ctrl_env_cfg.sv

diff --git a/hw/ip/sram_ctrl/dv/env/sram_ctrl_env_cfg.sv b/hw/ip/sram_ctrl/dv/env/sram_ctrl_env_cfg.sv
index 30cc3a2..ad7e92f 100644
--- a/hw/ip/sram_ctrl/dv/env/sram_ctrl_env_cfg.sv
+++ b/hw/ip/sram_ctrl/dv/env/sram_ctrl_env_cfg.sv
@@ -40,9 +40,6 @@
     // Set up second RAL model for SRAM memory and associated collateral
     ral_model_names.push_back(sram_ral_name);
 
-    // both RAL models use same clock frequency
-    clk_freqs_mhz[sram_ral_name] = clk_freq_mhz;
-
     super.initialize(csr_base_addr);
     tl_intg_alert_fields[ral.status.bus_integ_error] = 1;
 
@@ -68,6 +65,12 @@
     m_tl_agent_cfgs[sram_ral_name].max_outstanding_req = 2;
   endfunction
 
+  function void post_randomize();
+    super.post_randomize();
+    // both RAL models use same clock frequency
+    clk_freqs_mhz[sram_ral_name] = clk_freq_mhz;
+  endfunction
+
   // Override the default implementation in dv_base_env_cfg.
   //
   // This is required for the SRAM environment for reuse at the chip level as 2 different