ARM: imx: drop epit timer initialization from imx35 clock driver

EPIT provides another timer implementation besides the default GPT
timer.  The imx35 clock driver will use EPIT timer when option
CONFIG_MXC_USE_EPIT is enabled.  However, initializing timers from
clock driver is a workaround solution and causes problem when we move
clock drivers into driver/clk.

Let's simply drop the EPIT initialization from there.  If people really
want this EPIT option, EPIT timer driver needs to be reworked to do the
initialization in a standard way - use CLOCKSOURCE_OF_DECLARE() with
device tree support.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>