BugLink: https://bugs.launchpad.net/bugs/1885932

[ Upstream commit 44734a59 ]

m66592_free_request() is called under label "err_add_udc"
and "clean_up", and m66592->ep0_req is not set to NULL after
first free, leading to a double-free. Fix this issue by
setting m66592->ep0_req to NULL after the first free.

Fixes: 0f91349b ("usb: gadget: convert all users to the new udc infrastructure")
Signed-off-by: Qiushi Wu <wu000273@umn.edu>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kelsey Skunberg <kelsey.skunberg@canonical.com>