Rename common ns16550 constants with UART_ prefix to prevent conflicts

Fix problems introduced in commit
7b5611cdd12ca0cc33f994f0d4a4454788fc3124 [inka4x0: Add hardware
diagnosis functions for inka4x0] which redefined MSR_RI which is
already used on PowerPC systems.

Also eliminate redundant definitions in ps2mult.h.  More cleanup will
be needed for other redundant occurrences though.

Signed-off-by: Detlev Zundel <dzu@denx.de>
diff --git a/board/linkstation/avr.c b/board/linkstation/avr.c
index fda1b91..782b24a 100644
--- a/board/linkstation/avr.c
+++ b/board/linkstation/avr.c
@@ -90,12 +90,12 @@
 	 */
 	AVR_port->lcr = 0x00;
 	AVR_port->ier = 0x00;
-	AVR_port->lcr = LCR_BKSE;
+	AVR_port->lcr = UART_LCR_BKSE;
 	AVR_port->dll = clock_divisor & 0xff;
 	AVR_port->dlm = (clock_divisor >> 8) & 0xff;
-	AVR_port->lcr = LCR_WLS_8 | LCR_PEN | LCR_EPS;
+	AVR_port->lcr = UART_LCR_WLS_8 | UART_LCR_PEN | UART_LCR_EPS;
 	AVR_port->mcr = 0x00;
-	AVR_port->fcr = FCR_FIFO_EN | FCR_RXSR | FCR_TXSR;
+	AVR_port->fcr = UART_FCR_FIFO_EN | UART_FCR_RXSR | UART_FCR_TXSR;
 
 	miconCntl_DisWDT();