net: dsa: fix value check in bcm_sf2_sw_probe()

net: dsa: fix value check in bcm_sf2_sw_probe()

in bcm_sf2_sw_probe(), check the return value of clk_prepare_enable()
and return the error code if clk_prepare_enable() returns an
unexpected value.

Fixes: e9ec5c3bd238 ("net: dsa: bcm_sf2: request and handle clocks")
Signed-off-by: Yuanjun Gong <ruc_gongyuanjun@163.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/20230726170506.16547-1-ruc_gongyuanjun@163.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>