usb: gadget: uvc: Use macro for interrupt endpoint status size instead of using a MAGIC number

This patch adds a MACRO for the UVC video control status (interrupt) endpoint and
removes the magic number which was being used earlier.

Some UDCs have issues supporting an interrupt IN endpoint having a max packet
size less than a particular value (say 32). It is easier in that case to simply
change the MACRO value instead of changing the max packet size value at a
number of locations.

Signed-off-by: Bhupesh Sharma <bhupesh.sharma@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

Author: bhupesh-sharma

drivers/usb/gadget/f_uvc.c

@@ -59,6 +59,8 @@ static struct usb_gadget_strings *uvc_function_strings[] = {
 #define UVC_INTF_VIDEO_CONTROL			0
 #define UVC_INTF_VIDEO_STREAMING		1
 
+#define STATUS_BYTECOUNT			16	/* 16 bytes status */
+
 static struct usb_interface_assoc_descriptor uvc_iad __initdata = {
 	.bLength		= sizeof(uvc_iad),
 	.bDescriptorType	= USB_DT_INTERFACE_ASSOCIATION,
@@ -87,15 +89,15 @@ static struct usb_endpoint_descriptor uvc_control_ep __initdata = {
 	.bDescriptorType	= USB_DT_ENDPOINT,
 	.bEndpointAddress	= USB_DIR_IN,
 	.bmAttributes		= USB_ENDPOINT_XFER_INT,
-	.wMaxPacketSize		= cpu_to_le16(16),
+	.wMaxPacketSize		= cpu_to_le16(STATUS_BYTECOUNT),
 	.bInterval		= 8,
 };
 
 static struct uvc_control_endpoint_descriptor uvc_control_cs_ep __initdata = {
 	.bLength		= UVC_DT_CONTROL_ENDPOINT_SIZE,
 	.bDescriptorType	= USB_DT_CS_ENDPOINT,
 	.bDescriptorSubType	= UVC_EP_INTERRUPT,
-	.wMaxTransferSize	= cpu_to_le16(16),
+	.wMaxTransferSize	= cpu_to_le16(STATUS_BYTECOUNT),
 };
 
 static struct usb_interface_descriptor uvc_streaming_intf_alt0 __initdata = {