Fix sleeping in atomic context warning as reported by the Smatch static
checker tool by replacing disable_irq->disable_irq_nosync.

Reported by: Dan Carpenter <dan.carpenter@linaro.org>

Fixes: 8749061b ("tty: serial: sh-sci: Add RZ/G2L SCIFA DMA tx support")
Cc: stable@kernel.org
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20230704154818.406913-1-biju.das.jz@bp.renesas.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>