arm64: link with -z norelro regardless of CONFIG_RELOCATABLE

With CONFIG_EXPERT=y, CONFIG_KASAN=y, CONFIG_RANDOMIZE_BASE=n,
CONFIG_RELOCATABLE=n, we observe the following failure when trying to
link the kernel image with LD=ld.lld:

error: section: .exit.data is not contiguous with other relro sections

ld.lld defaults to -z relro while ld.bfd defaults to -z norelro. This
was previously fixed, but only for CONFIG_RELOCATABLE=y.

Fixes: 3bbd3db864 ("arm64: relocatable: fix inconsistencies in linker script and options")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201016175339.2429280-1-ndesaulniers@google.com
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/Makefile

@@ -10,13 +10,13 @@
 #
 # Copyright (C) 1995-2001 by Russell King
 
-LDFLAGS_vmlinux	:=--no-undefined -X
+LDFLAGS_vmlinux	:=--no-undefined -X -z norelro
 
 ifeq ($(CONFIG_RELOCATABLE), y)
 # Pass --no-apply-dynamic-relocs to restore pre-binutils-2.27 behaviour
 # for relative relocs, since this leads to better Image compression
 # with the relocation offsets always being zero.
-LDFLAGS_vmlinux		+= -shared -Bsymbolic -z notext -z norelro \
+LDFLAGS_vmlinux		+= -shared -Bsymbolic -z notext \
 			$(call ld-option, --no-apply-dynamic-relocs)
 endif