USB/host: Cleanup unneccessary irq disable code

Because the IRQF_DISABLED as the flag is now a NOOP and has been
deprecated and in hardirq context the interrupt is disabled.

so in usb/host code:
Removing the usage of flag IRQF_DISABLED;
Removing the calling local_irq save/restore actions in irq
handler usb_hcd_irq();

Signed-off-by: liu chuansheng <chuansheng.liu@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>