The whole function body is encapsulated inside an if-condition. Reverse
the if logic and early return to remove one indentation level.

Also turn two nested ifs into a single one at the end of the function.
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Théo Lebrun <theo.lebrun@bootlin.com>
Link: https://lore.kernel.org/r/20231207-mbly-uart-v6-7-e384afa5e78c@bootlin.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>