PCI: histb: Fix error path of histb_pcie_host_enable()

If clk_prepare_enable() call fails on a particular clock, we should not
call clk_disable_unprepare() on this clock, but on the clocks that
succeed from clk_prepare_enable() previously.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>