Blackfin: bfin_serial.h: turn default port wrappers into stubs

Any consumer that needs to access the MMRs has to provide these helpers,
so make the default into useless stubs.
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

arch/blackfin/include/asm/bfin_serial.h

@@ -184,7 +184,7 @@ struct bfin_uart_regs {
 #undef __BFP
 
 #ifndef port_membase
-# define port_membase(p) (((struct bfin_serial_port *)(p))->port.membase)
+# define port_membase(p) 0
 #endif
 
 #define UART_GET_CHAR(p)      bfin_read16(port_membase(p) + OFFSET_RBR)
@@ -235,10 +235,10 @@ struct bfin_uart_regs {
 #define UART_SET_DLAB(p)      do { UART_PUT_LCR(p, UART_GET_LCR(p) | DLAB); SSYNC(); } while (0)
 
 #ifndef put_lsr_cache
-# define put_lsr_cache(p, v) (((struct bfin_serial_port *)(p))->lsr = (v))
+# define put_lsr_cache(p, v)
 #endif
 #ifndef get_lsr_cache
-# define get_lsr_cache(p)    (((struct bfin_serial_port *)(p))->lsr)
+# define get_lsr_cache(p) 0
 #endif
 
 /* The hardware clears the LSR bits upon read, so we need to cache