spi: sh-msiof: Use dev_warn_once() instead of open-coding

Use the helper introduced by commit e135303bd5bebcd2 ("device: Add
dev_<level>_once variants") instead of open-coding the same
functionality.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
1 file changed