usb: f_gsi: Do not override config item name

Rndis gsi driver updates the config item type and in the
process also overrides config item name as empty string. This
can cause confusion as symlined config item appears as empty
file name.

Change-Id: Ic05e50d753a79ca9aa08f393b6bab0a5789cd03a
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>