clk: berlin: bg2q: remove non-exist "smemc" gate clock

The "smemc" clock is removed on BG2Q SoCs. In fact, bit19 of clkenable
register is for nfc. Current code use bit19 for non-exist "smemc"
incorrectly, this prevents eMMC from working due to the sdhci's
"core" clk is still gated.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Michael Turquette <mturquette@linaro.org>