util/inteltool: suggest booting with iomem=relaxed

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Change-Id: Ib80efd7d1ba516cb0ae4bdb86f95877855195ce0
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63999
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/inteltool/rootcmplx.c

@@ -135,6 +135,7 @@ int print_rcba(struct pci_dev *sb)
 
 	if (rcba == NULL) {
 		perror("Error mapping RCBA");
+		printf("Try booting with iomem=relaxed.\n");
 		exit(1);
 	}