ARM: 8245/1: pcmcia: soc-common: enable/disable socket clocks

Call clk_prepare_enable() during hw_init() and clk_disable_unprepare()
during hw_shutdown() to ensure that the clock rates returned by
clk_get_rate() are correct.

It is safe to call enable/disable functions even on NULL clock, so this
patch will not break cases when the socket clock is not set.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>