Don't zero r1 on entry to the dynamic linker.

There's no need: __linker_init only takes one argument.

Also remove the arm __CTOR_LIST__; we use .init_array and .fini_array instead
of .ctor and .dtor anyway, and I don't think we've ever supported the latter.

Change-Id: Ifc91a5a90c6aa39d674bf0509a7af2e1ff0beddd
diff --git a/linker/arch/arm64/begin.S b/linker/arch/arm64/begin.S
index c96ede7..a6ea583 100644
--- a/linker/arch/arm64/begin.S
+++ b/linker/arch/arm64/begin.S
@@ -30,8 +30,7 @@
 
 ENTRY(_start)
   mov x0, sp
-  mov x1, xzr
-  bl  __linker_init
+  bl __linker_init
 
   /* linker init returns the _entry address in the main image */
   br x0