dm: ns16550: Support non-byte register spacing with driver model

Allow this driver to support boards where the register shift is not 0.
This fixes some compiler warnings which appear in that case.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index 362f2ee..6131299 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -57,7 +57,7 @@
 
 #ifdef CONFIG_DM_SERIAL
 
-static inline void serial_out_shift(unsigned char *addr, int shift, int value)
+static inline void serial_out_shift(void *addr, int shift, int value)
 {
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 	outb(value, (ulong)addr);
@@ -72,7 +72,7 @@
 #endif
 }
 
-static inline int serial_in_shift(unsigned char *addr, int shift)
+static inline int serial_in_shift(void *addr, int shift)
 {
 #ifdef CONFIG_SYS_NS16550_PORT_MAPPED
 	return inb((ulong)addr);
@@ -114,9 +114,11 @@
 
 /* We can clean these up once everything is moved to driver model */
 #define serial_out(value, addr)	\
-	ns16550_writeb(com_port, addr - (unsigned char *)com_port, value)
+	ns16550_writeb(com_port, \
+		(unsigned char *)addr - (unsigned char *)com_port, value)
 #define serial_in(addr) \
-	ns16550_readb(com_port, addr - (unsigned char *)com_port)
+	ns16550_readb(com_port, \
+		(unsigned char *)addr - (unsigned char *)com_port)
 #endif
 
 static inline int calc_divisor(NS16550_t port, int clock, int baudrate)