serial: Fix UPIO_MEM comment

The original semantics of UPIO_MEM did not include the notion of bitness
and endianness; different drivers used UPIO_MEM to refer to their original
mmio bitness/endianness. For example, for the 8250 driver this is 8-bit LE
but for the amba-pl011 driver this is 16-bit LE. Since UPIO_* values are
userspace ABI via TIOCGSERIAL/TIOCSSERIAL ioctls, the original meaning of
UPIIO_MEM must remain as it was: the original mmio stride/width/endianness
of the driver.
Signed-off-by: NPeter Hurley <peter@hurleysoftware.com>
Acked-by: NTimur Tabi <timur@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/serial_core.h

@@ -145,7 +145,7 @@ struct uart_port {
 
 #define UPIO_PORT		(SERIAL_IO_PORT)	/* 8b I/O port access */
 #define UPIO_HUB6		(SERIAL_IO_HUB6)	/* Hub6 ISA card */
-#define UPIO_MEM		(SERIAL_IO_MEM)		/* 8b MMIO access */
+#define UPIO_MEM		(SERIAL_IO_MEM)		/* driver-specific */
 #define UPIO_MEM32		(SERIAL_IO_MEM32)	/* 32b little endian */
 #define UPIO_AU			(SERIAL_IO_AU)		/* Au1x00 and RT288x type IO */
 #define UPIO_TSI		(SERIAL_IO_TSI)		/* Tsi108/109 type IO */