Arm: drop ENFORCE_UNIQUE_SYMBOLS=y workaround again

Both arm<NN>/head.S and arm<NN>/mmu/head.S have a local symbol "fail".
Without a .file directive locals will be associated with the path-less
object filename (head.o). Hence the two symbol names collide. Add .file,
also in arm<NN>/mpu/head.S for consistency.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

xen/arch/arm/Makefile

@@ -91,9 +91,6 @@ include scripts/Makefile.link
 # Suppress orphan section checking for the time being.
 orphan-handling-y :=
 
-# Downgrade duplicate symbol errors to warnings for the time being.
-syms-warn-dup-$(CONFIG_ENFORCE_UNIQUE_SYMBOLS) := --warn-dup
-
 .PHONY: include
 include:
 

xen/arch/arm/arm32/head.S

@@ -17,6 +17,8 @@
  * GNU General Public License for more details.
  */
 
+        .file __FILE__
+
 #include <asm/page.h>
 #include <asm/early_printk.h>
 

xen/arch/arm/arm32/mmu/head.S

@@ -5,6 +5,8 @@
  * Arm32 MMU specific start-of-day code.
  */
 
+        .file __FILE__
+
 #include <asm/page.h>
 #include <asm/early_printk.h>
 

xen/arch/arm/arm32/mpu/head.S

@@ -3,6 +3,8 @@
  * Start-of-day code for an Armv8-R-AArch32 MPU system.
  */
 
+    .file __FILE__
+
 #include <asm/arm32/macros.h>
 #include <asm/arm32/sysregs.h>
 #include <asm/cpregs.h>

xen/arch/arm/arm64/head.S

@@ -20,6 +20,8 @@
  * GNU General Public License for more details.
  */
 
+        .file __FILE__
+
 #include <asm/page.h>
 #include <asm/early_printk.h>
 

xen/arch/arm/arm64/mmu/head.S

@@ -5,6 +5,8 @@
  * Arm64 MMU specific start-of-day code.
  */
 
+        .file __FILE__
+
 #include <asm/page.h>
 #include <asm/early_printk.h>
 

xen/arch/arm/arm64/mpu/head.S

@@ -3,6 +3,8 @@
  * Start-of-day code for an Armv8-R MPU system.
  */
 
+    .file __FILE__
+
 #include <asm/mpu/regions.inc>
 
 /*