Revert "arm64: kexec: make dtb_mem always enabled"

Adding crash dump support to 'kexec_file' is going to extend 'struct
kimage_arch' with more 'kexec_file'-specific members. The cleanup here
then starts to get in the way, so revert it.

This reverts commit 62151678.
Reported-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/kexec.h

@@ -90,14 +90,14 @@ static inline void crash_prepare_suspend(void) {}
 static inline void crash_post_resume(void) {}
 #endif
 
+#ifdef CONFIG_KEXEC_FILE
 #define ARCH_HAS_KIMAGE_ARCH
 
 struct kimage_arch {
 	void *dtb;
-	phys_addr_t dtb_mem;
+	unsigned long dtb_mem;
 };
 
-#ifdef CONFIG_KEXEC_FILE
 extern const struct kexec_file_ops kexec_image_ops;
 
 struct kimage;

arch/arm64/kernel/machine_kexec.c

@@ -203,7 +203,11 @@ void machine_kexec(struct kimage *kimage)
 	 * In kexec_file case, the kernel starts directly without purgatory.
 	 */
 	cpu_soft_restart(reboot_code_buffer_phys, kimage->head, kimage->start,
-			 kimage->arch.dtb_mem);
+#ifdef CONFIG_KEXEC_FILE
+						kimage->arch.dtb_mem);
+#else
+						0);
+#endif
 
 	BUG(); /* Should never get here. */
 }