kvm: arm64: Only define __kvm_ex_table for CONFIG_KVM

Minor cleanup that only creates __kvm_ex_table ELF section and
related symbols if CONFIG_KVM is enabled. Also useful as more
hyp-specific sections will be added.
Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200922204910.7265-4-dbrazdil@google.com

arch/arm64/kernel/vmlinux.lds.S

@@ -22,11 +22,15 @@ ENTRY(_text)
 jiffies = jiffies_64;
 
 
+#ifdef CONFIG_KVM
 #define HYPERVISOR_EXTABLE					\
 	. = ALIGN(SZ_8);					\
 	__start___kvm_ex_table = .;				\
 	*(__kvm_ex_table)					\
 	__stop___kvm_ex_table = .;
+#else /* CONFIG_KVM */
+#define HYPERVISOR_EXTABLE
+#endif
 
 #define HYPERVISOR_TEXT					\
 	/*						\