[PATCH 4.9 033/206] usb: gadget: composite: Test get_alt() presence instead of set_alt()

4.9-stable review patch. If anyone has any objections, please let me know. -- From: Krzysztof Opasiak commit 7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f upstream. By convention (according to doc) if function does not provide get_alt() callback composite

[PATCH 4.9 033/206] usb: gadget: composite: Test get_alt() presence instead of set_alt()

4.9-stable review patch. If anyone has any objections, please let me know. -- From: Krzysztof Opasiak commit 7e4da3fcf7c9fe042f2f7cb7bf23861a899b4a8f upstream. By convention (according to doc) if function does not provide get_alt() callback composite framework should assume