usb: gadget: udc: core: Revise comments for USB ep enable/disable

The usb_ep_disable() and usb_ep_enable() routines are being widely
used in atomic/interrupt context by function drivers.  Hence, the
statement about it being able to only run in process context may
not be true.  Add an explicit comment mentioning that it can be used
in atomic context.

Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/1635365407-31337-2-git-send-email-quic_wcheng@quicinc.com


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