Revert "uart: pl011: Improve LCRH register access decision"

This reverts commit 09dcc7dfc05b31bf0bbcd1511cd1a2644908d5c8 as with
this patch the serial console is broken on lots of platforms.

Reported-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Jun Nie <jun.nie@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/amba-pl011.c

@@ -249,11 +249,6 @@ struct uart_amba_port {
 #endif
 };
 
-static bool is_implemented(struct uart_amba_port *uap, unsigned int reg)
-{
-	return uap->reg_lut[reg] != (u16)~0;
-}
-
 static unsigned int pl011_readw(struct uart_amba_port *uap, int index)
 {
 	WARN_ON(index > REG_NR);
@@ -1654,7 +1649,7 @@ static int pl011_hwinit(struct uart_port *port)
 static void pl011_write_lcr_h(struct uart_amba_port *uap, unsigned int lcr_h)
 {
 	pl011_writew(uap, lcr_h, uap->lcrh_rx);
-	if (is_implemented(uap, REG_ST_LCRH_RX)) {
+	if (uap->lcrh_rx != uap->lcrh_tx) {
 		int i;
 		/*
 		 * Wait 10 PCLKs before writing LCRH_TX register,
@@ -1789,7 +1784,7 @@ static void pl011_disable_uart(struct uart_amba_port *uap)
 	 * disable break condition and fifos
 	 */
 	pl011_shutdown_channel(uap, uap->lcrh_rx);
-	if (is_implemented(uap, REG_ST_LCRH_RX))
+	if (uap->lcrh_rx != uap->lcrh_tx)
 		pl011_shutdown_channel(uap, uap->lcrh_tx);
 }