regulator: rt5739: Spelling s/Rcihtek/Richtek/

Fix a misspelling of "Richtek".

Fixes: 4536f3b9 ("regulator: Add support for Richtek RT5739 voltage regulator")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/05f26d8e1e527f8b3fd2828f75ce2174e19c69e7.1678188171.git.geert+renesas@glider.be


Signed-off-by: Mark Brown <broonie@kernel.org>