x86/crash: use SZ_1M macro instead of hardcoded value

Use SZ_1M macro instead of hardcoded 1<<20 to make code more readable.

Link: https://lkml.kernel.org/r/20240102144905.110047-3-ytcoode@gmail.comSigned-off-by: Yuntao Wang <ytcoode@gmail.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Sourabh Jain <sourabhjain@linux.ibm.com>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/x86/kernel/crash.c

@@ -170,7 +170,7 @@ static int elf_header_exclude_ranges(struct crash_mem *cmem)
 	int ret = 0;
 
 	/* Exclude the low 1M because it is always reserved */
-	ret = crash_exclude_mem_range(cmem, 0, (1<<20)-1);
+	ret = crash_exclude_mem_range(cmem, 0, SZ_1M - 1);
 	if (ret)
 		return ret;