clk: clk-gpio: use dev_err_probe for gpio-get failure

This is a real driver and dev_err_probe will hide the distinction between
EPROBE_DEFER and other errors automatically, so there is no need to
open-code this.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20240906082511.2963890-4-heiko@sntech.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>