KVM: selftests: Add printf attribute to _no_printf()

Annotate the KVM selftests' _no_printf() with the printf format attribute
so that the compiler can help check parameters provided to pr_debug() and
pr_info() irrespective of DEBUG and QUIET being defined.

[reinette: move attribute right after storage class, rework changelog]

Signed-off-by: Isaku Yamahata <[e-mail]>
Signed-off-by: Reinette Chatre <[e-mail]>
Link: https://lore.kernel.org/r/898ec01[e-mail]
Signed-off-by: Sean Christopherson <[e-mail]>

tools/testing/selftests/kvm/include/test_util.h

···
 
 #define msecs_to_usecs(msec)    ((msec) * 1000ULL)
 
-static inline int _no_printf(const char *format, ...) { return 0; }
+static inline __printf(1, 2) int _no_printf(const char *format, ...) { return 0; }
 
 #ifdef DEBUG
 #define pr_debug(...) printf(__VA_ARGS__)