ArmVirtPkg: clean up FP enabling code

UEFI defines that FP support is required on AArch64, whereas ArmVirtPkg
enables it anyway on Arm. But when it's enabled, C code can generate
instructions targeting FP registers, so:

- move ArmEnableVFP call to asm
- make it unconditional on AArch64

Signed-off-by: Leif Lindholm <leif.lindholm@oss.qualcomm.com>

ArmVirtPkg/PrePi/AArch64/ModuleEntryPoint.S

@@ -20,11 +20,9 @@ ASM_FUNC(_ModuleEntryPoint)
 0:mov   x28, x0             // preserve DTB pointer
   mov   x27, x1             // preserve base of image pointer
 
-#if (FixedPcdGet32 (PcdVFPEnabled))
   // Enable Floating Point. This needs to be done before entering C code, which
   // may use FP/SIMD registers.
   bl    ArmEnableVFP
-#endif
 
   bl    ASM_PFX(DiscoverDramFromDt)
 

ArmVirtPkg/PrePi/Arm/ArchPrePi.c

@@ -13,8 +13,4 @@ ArchInitialize (
   VOID
   )
 {
-  // Enable Floating Point
-  if (FixedPcdGet32 (PcdVFPEnabled)) {
-    ArmEnableVFP ();
-  }
 }

ArmVirtPkg/PrePi/Arm/ModuleEntryPoint.S

@@ -12,6 +12,12 @@ ASM_FUNC(_ModuleEntryPoint)
   // Do early platform specific actions
   bl    ASM_PFX(ArmPlatformPeiBootAction)
 
+#if (FixedPcdGet32 (PcdVFPEnabled))
+  // Enable Floating Point. AArch64 uses hardfloat ABI so needs this done before
+  // calling any C code. Arm does not, but let's keep the ports aligned.
+  bl    ArmEnableVFP
+#endif
+
   // Get ID of this CPU in Multicore system
   bl    ASM_PFX(ArmReadMpidr)
   // Keep a copy of the MpId register value