serial: 8250_em: Fix UART port type

As per HW manual for  EMEV2 "R19UH0040EJ0400 Rev.4.00", the UART
IP found on EMMA mobile SoC is Register-compatible with the
general-purpose 16750 UART chip. Fix UART port type as 16750 and
enable 64-bytes fifo support.

Fixes: 22886ee9 ("serial8250-em: Emma Mobile UART driver V2")
Cc: stable@vger.kernel.org
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230227114152.22265-2-biju.das.jz@bp.renesas.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_em.c

@@ -106,8 +106,8 @@ static int serial8250_em_probe(struct platform_device *pdev)
 	memset(&up, 0, sizeof(up));
 	up.port.mapbase = regs->start;
 	up.port.irq = irq;
-	up.port.type = PORT_UNKNOWN;
-	up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
+	up.port.type = PORT_16750;
+	up.port.flags = UPF_FIXED_PORT | UPF_IOREMAP | UPF_FIXED_TYPE;
 	up.port.dev = &pdev->dev;
 	up.port.private_data = priv;