ARM: imx6q: add the missing esai_ahb clock

ARM: imx6q: add the missing esai_ahb clock

The esai_ahb clock is derived from ahb and used to provide ESAI the
capability of register accessing and FSYS clock source for I2S clocks
dividing.  The gate bits of this esai_ahb clock are shared with the
esai clock -- the baud clock, so we need to call imx_clk_gate2_shared()
for these two clocks.

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>