clk: berlin: bg2q: remove CLK_IGNORE_UNUSED flag for sdio clk

Since we have added the necessary two clks' properties in dts, we can
remove the "sdio" clk's CLK_IGNORE_UNUSED flag now.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>