MIPS: AR7: ensure the port type's FCR value is used

Since commit aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt
trigger I/F of FIFO buffers"), the port's default FCR value isn't used
in serial8250_do_set_termios anymore, but copied over once in
serial8250_config_port and then modified as needed.

Unfortunately, serial8250_config_port will never be called if the port
is shared between kernel and userspace, and the port's flag doesn't have
UPF_BOOT_AUTOCONF, which would trigger a serial8250_config_port as well.

This causes garbled output from userspace:

[ 5.220000] random: procd urandom read with 49 bits of entropy available
ers
[kee

Fix this by forcing it to be configured on boot, resulting in the
expected output:

[ 5.250000] random: procd urandom read with 50 bits of entropy available
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level

Fixes: aef9a7bd9b67 ("serial/uart/8250: Add tunable RX interrupt trigger I/F of FIFO buffers")
Signed-off-by: Jonas Gorski <[e-mail]>
Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Yoshihiro YUNOMAE <[e-mail]>
Cc: Florian Fainelli <[e-mail]>
Cc: Nicolas Schichan <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Patchwork: https://patchwork.linux-mips.org/patch/17544/
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/ar7/platform.c

···
 	uart_port.type		= PORT_AR7;
 	uart_port.uartclk	= clk_get_rate(bus_clk) / 2;
 	uart_port.iotype	= UPIO_MEM32;
-	uart_port.flags		= UPF_FIXED_TYPE;
+	uart_port.flags		= UPF_FIXED_TYPE | UPF_BOOT_AUTOCONF;
 	uart_port.regshift	= 2;
 
 	uart_port.line		= 0;