ARM: dts: berlin: fix io clk and add missing core clk for BG2Q sdhci2 host

On BG2Q, the sdhci2 host uses nfcecc for "io" clk and nfc for "core" clk.
The shdci2 can't work without this patch due to the "core" clk is gated.

Cc: stable@vger.kernel.org # 3.16+
Fixes: 0d859a6a ("ARM: dts: berlin: add the SDHCI nodes for the BG2Q")
Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>