ibm_rtl: fix printk format warning

Fix printk format warning:

drivers/platform/x86/ibm_rtl.c:305:warning: format '%#llx' expects type 'long long unsigned int', but argument 2 has type 'phys_addr_t'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Keith Mannthey <kmannth@us.ibm.com>
Cc: Vernon Mauery <vernux@us.ibm.com>
Cc: platform-driver-x86@vger.kernel.org
Cc: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>