Staging: ft1000-usb: Fix Smatch Warning in ft1000_hw.c

This patch fixes following smatch warning:
/drivers/staging/ft1000/ft1000-usb/ft1000_hw.c:1148 ft1000_proc_drvmsg() warn: returning -1 instead of -ENOMEM is sloppy

Signed-off-by: Monam Agarwal <monamagarwal123@gmail.com>
Acked-by: Nick Kossifidis <mickflemm@gmail.com>
Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>