tmem: reduce severity of log messages

Otherwise they can be used by a guest to spam the hypervisor log with
all settings at their defaults.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx>

--- a/xen/common/tmem.c
+++ b/xen/common/tmem.c
@@ -16,6 +16,7 @@
 
 #ifdef __XEN__
 #include <xen/tmem_xen.h> /* host-specific (eg Xen) code goes here */
+#define printk(fmt, args...) gdprintk(XENLOG_INFO, fmt, ##args)
 #endif
 
 #include <xen/tmem.h>