USB: Change acm_iad_descriptor bFunctionProtocol to USB_CDC_ACM_PROTO_AT_V25TER

The protocol code is set 00 in IAD and it's set to 01 in ACM control
interface descriptor in f_acm.c file. Due to this, windows is unable to
install the modem(ACM) driver based on class-subclass-protocol matching.

This patch corrects the protocol code in ACM IAD to the same as in
acm_control_interface_desc protocol code.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Praveena Nadahally <praveen.nadahally@stericsson.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>