wifi: rtw89: usb: fix leak in rtw89_usb_write_port()

wifi: rtw89: usb: fix leak in rtw89_usb_write_port()

When there is an attempt to write data and RTW89_FLAG_UNPLUGGED is set,
this means device is disconnected and no urb is submitted.  Return
appropriate error code to the caller to properly free the allocated
resources.

Found by Linux Verification Center (linuxtesting.org).

Fixes: 2135c28be6a8 ("wifi: rtw89: Add usb.{c,h}")
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20251104135720.321110-3-pchelkin@ispras.ru