Add console_*printf() functions.

Add support for the missing console_vprintf() and console_printf()
functions.

include/sys/console.h

@@ -0,0 +1,20 @@
+#ifndef	_SPL_CONSOLE_H
+#define	_SPL_CONSOLE_H
+
+void
+console_vprintf(const char *fmt, va_list args)
+{
+        vprintk(fmt, args);
+}
+
+void
+console_printf(const char *fmt, ...)
+{
+        va_list args;
+
+        va_start(args, fmt);
+        console_vprintf(fmt, args);
+        va_end(args);
+}
+
+#endif /* _SPL_CONSOLE_H */