leds: max77705: Function return instead of variable assignment

Coverity noticed that assigning value -EINVAL to 'ret' in the if
statement is useless because 'ret' is overwritten a few lines later.
However, after inspect the code, this warning reveals that we need to
return -EINVAL instead of the variable assignment. So, fix it.

Coverity-id: 1646104
Fixes: aebb5fc9 ("leds: max77705: Add LEDs support")
Signed-off-by: Len Bao <len.bao@gmx.us>
Link: https://lore.kernel.org/r/20250727075649.34496-1-len.bao@gmx.us


Signed-off-by: Lee Jones <lee@kernel.org>