usb: gadget: f_uac2: fix non-newline-terminated function name

[ Upstream commit e60284b6 ]

Most writes to configfs handle an optional newline, but do not require
it.  By using the number of bytes written as the limit for scnprintf()
it is guaranteed that the final character in the buffer will be
overwritten.

This is expected if it is a newline but is undesirable when a string is
written "as-is" (as libusbgx does, for example).

Update the store function to strip an optional newline, matching the
behaviour of usb_string_copy().

Signed-off-by: John Keeping <jkeeping@inmusicbrands.com>
Link: https://lore.kernel.org/r/20240708142553.3995022-1-jkeeping@inmusicbrands.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: 94993277 ("usb: gadget: f_uac2: fix return value for UAC2_ATTRIBUTE_STRING store")
Signed-off-by: Sasha Levin <sashal@kernel.org>