serial: 8520_ce4100: Reuse mem_serial_in() in ce4100_mem_serial_in()

In one place in ce4100_mem_serial_in() the code may be replaced with
mem_serial_in() call. Do it so and collapse two conditionals into one.

Suggested-by: Jiri Slaby <jirislaby@kernel.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20250701134200.2621898-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: andy-shev

drivers/tty/serial/8250/8250_ce4100.c

@@ -35,13 +35,8 @@ static u32 ce4100_mem_serial_in(struct uart_port *p, unsigned int offset)
 {
 	u32 ret, ier, lsr;
 
-	if (offset != UART_IIR)
-		return mem_serial_in(p, offset);
-
-	offset <<= p->regshift;
-
-	ret = readl(p->membase + offset);
-	if (!(ret & UART_IIR_NO_INT))
+	ret = mem_serial_in(p, offset);
+	if (offset != UART_IIR || !(ret & UART_IIR_NO_INT))
 		return ret;
 
 	/* see if the TX interrupt should have really set */