fpga altera-hps2fpga: disable/unprepare clock on error in alt_fpga_bridge_probe()

If either _alt_hps2fpga_enable_set() or fpga_bridge_register() fail in
alt_fpga_bridge_probe(), the clock remains enabled and prepared. Also,
in the error path for _alt_hps2fpga_enable_set() a call to
fpga_bridge_unregister() is made even though the bridge was not
registered yet.

Remove the unnecessary call to fpga_bridge_unregister() and call
clk_disable_unprepare() in both error paths in order to make sure the
clock gets properly disabled and unprepared.

Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>