driver core: unexport static function create_syslog_header

Function create_syslog_header() is defined as static, so it should
not be exported.
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

drivers/base/core.c

@@ -2058,7 +2058,6 @@ create_syslog_header(const struct device *dev, char *hdr, size_t hdrlen)
 
 	return pos;
 }
-EXPORT_SYMBOL(create_syslog_header);
 
 int dev_vprintk_emit(int level, const struct device *dev,
 		     const char *fmt, va_list args)