ArmPkg: use helper to check for Security extensions in ArmArchTimerLib

Use the helper ArmHasSecurityExtensions () instead of accessing
ID_PFR1 directly. Only affects ARM build.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

ArmPkg/Library/ArmArchTimerLib/ArmArchTimerLib.c

@@ -56,7 +56,7 @@ TimerConstructor (
       // If the security extension is not implemented, set Timer Frequency
       // here.
       //
-      if ((ArmReadIdPfr1 () & ARM_PFR1_SEC) == 0x0) {
+      if (ArmHasSecurityExtensions ()) {
         ArmGenericTimerSetTimerFreq (PcdGet32 (PcdArmArchTimerFreqInHz));
       }
 #endif