clk: renesas: Use str_on_off() helper

clk: renesas: Use str_on_off() helper

[ Upstream commit aff664cc8cbc5c28e5aa57dc4201c34497f3c871 ]

Use the str_on_off() helper instead of open-coding the same operation.
Note that this does change the case of the flags, which doesn't matter
much for debug messages.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/622f8554dcb815c8fc73511a1a118c1724570fa9.1745840497.git.geert+renesas@glider.be
Stable-dep-of: b91401af6c00 ("clk: renesas: cpg-mssr: Read back reset registers to assure values latched")
Signed-off-by: Sasha Levin <sashal@kernel.org>