NVIDIA: SAUCE: serial: amba-pl011: Do not use IBRD

Tegra UART controllers does not support FBRD register, which cause it to
not support various standard baudrates that HW supports.

Use clk_set_rate to program UART clock rate instead.

Bug 5406304

Change-Id: I6fcf14b0186e54a6f418287791d80e12d17600a0
Signed-off-by: Kartik Rajput <kkartik@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/c/3rdparty/canonical/linux-noble/+/3441884
Reviewed-by: Laxman Dewangan <ldewangan@nvidia.com>
(cherry picked from commit daa72589899560fb3570b165163bd8e35cf704e1)
Reviewed-on: https://git-master.nvidia.com/r/c/3rdparty/canonical/linux-noble/+/3447941
GVS: buildbot_gerritrpt <buildbot_gerritrpt@nvidia.com>

drivers/tty/serial/amba-pl011.c

@@ -2173,11 +2173,15 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 	else
 		clkdiv = 16;
 
-	/*
-	 * Ask the core to calculate the divisor for us.
-	 */
+	if (uap->vendor->enable_car) {
+		baud = tty_termios_baud_rate(termios);
+		clk_set_rate(uap->clk, baud * clkdiv);
+	}
+	else {
 		baud = uart_get_baud_rate(port, termios, old, 0,
 					  port->uartclk / clkdiv);
+	}
+
 #ifdef CONFIG_DMA_ENGINE
 	/*
 	 * Adjust RX DMA polling rate with baud rate if not specified.
@@ -2186,10 +2190,12 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 		uap->dmarx.poll_rate = DIV_ROUND_UP(10000000, baud);
 #endif
 
+	if (!uap->vendor->enable_car) {
 		if (baud > port->uartclk / 16)
 			quot = DIV_ROUND_CLOSEST(port->uartclk * 8, baud);
 		else
 			quot = DIV_ROUND_CLOSEST(port->uartclk * 4, baud);
+	}
 
 	switch (termios->c_cflag & CSIZE) {
 	case CS5:
@@ -2261,6 +2267,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 			old_cr &= ~ST_UART011_CR_OVSFACT;
 	}
 
+	if (!uap->vendor->enable_car) {
 		/*
 		* Workaround for the ST Micro oversampling variants to
 		* increase the bitrate slightly, by lowering the divisor,
@@ -2276,7 +2283,7 @@ pl011_set_termios(struct uart_port *port, struct ktermios *termios,
 		/* Set baud rate */
 		pl011_write(quot & 0x3f, uap, REG_FBRD);
 		pl011_write(quot >> 6, uap, REG_IBRD);
-
+	}
 	/*
 	 * ----------v----------v----------v----------v-----
 	 * NOTE: REG_LCRH_TX and REG_LCRH_RX MUST BE WRITTEN AFTER