Fix bug in usage of CONST segment in banked code. Use #pragma constseg

rtl837x_port.c

@@ -15,6 +15,7 @@
 #include "phy.h"
 
 #pragma codeseg BANK1
+#pragma constseg BANK1
 
 extern __code uint8_t * __code hex;
 extern __code uint16_t bit_mask[16];