arm: socfpga: vining: Set USB gadget manufacturer to Softing with capital S

This was configured in downstream, so it is likely that most of the
custom software used around the device depends on it. Make upstream
compatible.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Siew Chin Lim <elly.siew.chin.lim@intel.com>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Cc: Tien Fong Chee <tien.fong.chee@intel.com>