serial: 8250: sparse warning of incorrect type

fixed a sparse warning in 8250_core.c :
	incorrect type in assignment (different address spaces)

the warning was because an unsigned char pointer was being assigned to
a pointer of unsigned char __iomem type .
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250.h

@@ -56,7 +56,7 @@ struct old_serial_port {
 	unsigned int flags;
 	unsigned char hub6;
 	unsigned char io_type;
-	unsigned char *iomem_base;
+	unsigned char __iomem *iomem_base;
 	unsigned short iomem_reg_shift;
 	unsigned long irqflags;
 };