resource: Fix resource_size.cocci warnings

arch/x86/kernel/crash.c:627:34-37: ERROR: Missing resource_size with res
arch/x86/kernel/crash.c:528:16-19: ERROR: Missing resource_size with res

 Use resource_size function on resource object
 instead of explicit computation.

Generated by: scripts/coccinelle/api/resource_size.cocci

Fixes: 1d2e733b13 ("resource: Provide resource struct in resource walk callback")
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: kbuild-all@01.org
Cc: tipbuild@zytor.com
Cc: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20171107191801.GA91887@lkp-snb01

arch/x86/kernel/crash.c

@@ -525,7 +525,7 @@ static int memmap_entry_callback(struct resource *res, void *arg)
 	struct e820_entry ei;
 
 	ei.addr = res->start;
-	ei.size = res->end - res->start + 1;
+	ei.size = resource_size(res);
 	ei.type = cmd->type;
 	add_e820_entry(params, &ei);
 
@@ -624,7 +624,7 @@ static int determine_backup_region(struct resource *res, void *arg)
 	struct kimage *image = arg;
 
 	image->arch.backup_src_start = res->start;
-	image->arch.backup_src_sz = res->end - res->start + 1;
+	image->arch.backup_src_sz = resource_size(res);
 
 	/* Expecting only one range for backup region */
 	return 1;