staging: ks7010: fix error handling in ks7010_upload_firmware

This commit checks missing error code check when checking
if the firmware is running reading General Communication
Register A (GCR_A).

It also set ret to EBUSY if firmware is running before
copying it.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Reviewed-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>