usb: gadget: udc-xilinx: Fix an error handling path in 'xudc_probe()'

A successful 'clk_prepare_enable()' call should be balanced by a
corresponding 'clk_disable_unprepare()' call in the error handling path
of the probe, as already done in the remove function.

Fixes: 24749229 ("usb: gadget: udc-xilinx: Add clock support")
Reviewed-by: Shubhrajyoti Datta <shubhraj@xilinx.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/ec61a89b83ce34b53a3bdaacfd1413a9869cc608.1636302246.git.christophe.jaillet@wanadoo.fr


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>