xhci-ext-caps.c: Add missing platform_device_put() on error in xhci_create_intel_xhci_sw_pdev()

Add the missing platform_device_put() before return from
xhci_create_intel_xhci_sw_pdev() in the error handling case.

Fixes: 6ed151f2

 ("xhci-ext-caps.c: Add property to disable Intel SW switch")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20190905100001.128349-1-weiyongjun1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>