Staging: w35und: fix usb_control_msg() error handling in wb35_probe()

If successful, the usb_control_msg() function returns the number of
bytes transferred. Fix up wb35_probe() to only bail out if the function returns
a negative number. Also, fix up ieee80211_alloc_hw() error code to ENOMEM;
otherwise GCC complains that err might be undefined (and is right about that).

Acked-by: Pavel Machek <pavel@suse.cz>
Reported-and-tested-by: Sandro Bonazzola <sandro.bonazzola@gmail.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>