clk: mediatek: mt8183: Register 13MHz clock earlier for clocksource

The 13MHz clock should be registered before clocksource driver is
initialized. Use CLK_OF_DECLARE_DRIVER() to guarantee.

Fixes: acddfc2c ("clk: mediatek: Add MT8183 clock support")
Cc: <stable@vger.kernel.org>
Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>