[PATCH] serial: ns16550: Fix return-type warning

[Nikita Shubin]

Hi Tom.

On Thu, 2026-02-26 at 09:08 -0600, Tom Rini wrote:
> On Thu, Feb 26, 2026 at 05:02:47PM +0300, Nikita Shubin wrote:
> 
> > Fix compiler warning:
> > 
> > drivers/serial/ns16550.c: In function ‘serial_in_dynamic’:
> > drivers/serial/ns16550.c:153:1: warning: control reaches end
> >     of non-void function [-Wreturn-type]
> >   153 | }
> >       | ^
> > 
> > Fixes: 62cbde4c4e46 ("serial: ns16550: Support run-time
> > configuration")
> > Signed-off-by: Nikita Shubin <nikita.shubin at maquefel.me>
> 
> I assume this is from gcc-15.x ? Thanks.

Exactly, 

```
$ riscv64-unknown-linux-gnu-gcc --version
riscv64-unknown-linux-gnu-gcc (Gentoo 15.2.1_p20260214 p5) 15.2.1
20260214
```

To be precise.