sysmobts: Fix compiler warning by including utils.h

calib_file.c: In function 'next_calib_file_idx':
calib_file.c:126:3: warning: implicit declaration of function 'band_femto2osmo' [-Wimplicit-function-declaration]

src/osmo-bts-sysmo/calib_file.c

@@ -37,6 +37,7 @@
 #include "l1_if.h"
 #include "femtobts.h"
 #include "eeprom.h"
+#include "utils.h"
 
 struct calib_file_desc {
 	const char *fname;