x86/kdump: Remove the unused crash_copy_backup_region()

The crash_copy_backup_region() function is unused so remove it.
Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: bhe@redhat.com
Cc: dhowells@redhat.com
Cc: dyoung@redhat.com
Cc: ebiederm@xmission.com
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jürgen Gross <jgross@suse.com>
Cc: kexec@lists.infradead.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: vgoyal@redhat.com
Cc: x86-ml <x86@kernel.org>
Cc: Yi Wang <wang.yi59@zte.com.cn>
Link: https://lkml.kernel.org/r/20191017094347.20327-3-lijiang@redhat.com

arch/x86/include/asm/crash.h

@@ -3,7 +3,6 @@
 #define _ASM_X86_CRASH_H
 
 int crash_load_segments(struct kimage *image);
-int crash_copy_backup_region(struct kimage *image);
 int crash_setup_memmap_entries(struct kimage *image,
 		struct boot_params *params);
 void crash_smp_send_stop(void);