xen/arm: remove xen_phys_start and xenheap_phys_end from config.h

These two variables are stale variables, they only have declarations
in config.h, they don't have any definition and no any code is using
these two variables. So in this patch, we remove them from config.h.

Signed-off-by: Wei Chen <wei.chen@arm.com>
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>

xen/arch/arm/include/asm/config.h

@@ -209,8 +209,6 @@
 #define STACK_SIZE  (PAGE_SIZE << STACK_ORDER)
 
 #ifndef __ASSEMBLY__
-extern unsigned long xen_phys_start;
-extern unsigned long xenheap_phys_end;
 extern unsigned long frametable_virt_end;
 #endif