usb/xhci-plat: Set PM runtime as active on resume

usb/xhci-plat: Set PM runtime as active on resume

Follow suit of ohci-platform.c and perform pm_runtime_set_active() on
resume.

ohci-platform.c had a warning reported due to the missing
pm_runtime_set_active() [1].

[1] https://lore.kernel.org/lkml/20200323143857.db5zphxhq4hz3hmd@e107158-lin.cambridge.arm.com/

Signed-off-by: Qais Yousef <qais.yousef@arm.com>
CC: Tony Prisk <linux@prisktech.co.nz>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC: Mathias Nyman <mathias.nyman@intel.com>
CC: Oliver Neukum <oneukum@suse.de>
CC: linux-arm-kernel@lists.infradead.org
CC: linux-usb@vger.kernel.org
CC: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20200518154931.6144-2-qais.yousef@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>