usb: gadget: uvc: Correct documentation formatting

The documentation table added in a36afe78 ("usb: gadget: uvc: Add
new enable_interrupt_ep attribute") was incorrect, resulting in a new
warning when compiling the documentation.

Correct the formatting to resolve the warning.

Fixes: a36afe78 ("usb: gadget: uvc: Add new enable_interrupt_ep attribute")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com>
Link: https://lore.kernel.org/r/20230206151131.863960-1-dan.scally@ideasonboard.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/configfs-usb-gadget-uvc

@@ -17,12 +17,12 @@ Description:	Control descriptors
 
 		All attributes read only except enable_interrupt_ep:
 
-		================	=============================
+		===================	=============================
 		bInterfaceNumber	USB interface number for this
 					streaming interface
 		enable_interrupt_ep	flag to enable the interrupt
 					endpoint for the VC interface
-		================	=============================
+		===================	=============================
 
 What:		/config/usb-gadget/gadget/functions/uvc.name/control/class
 Date:		Dec 2014