Move reverse_bits*() to separate source file

reversing bits is not NR specific. Think of it like this: LTE code might
use reverse_bits*() as well, but in the old location, it would pull in a
bunch of NR dependencies that are superfluous.

openair2/NR_UE_PHY_INTERFACE/NR_IF_Module.c

@@ -35,6 +35,7 @@
 #include "NR_MAC_UE/mac_proto.h"
 #include "assertions.h"
 #include "SCHED_NR_UE/fapi_nr_ue_l1.h"
+#include "reverse_bits.h"
 #include "openair2/RRC/NR_UE/L2_interface_ue.h"
 
 #define MAX_IF_MODULES 100