drivers: base: fw: fix ret value when loading fw

When using the user mode helper to load firmwares the function _request_firmware
gets a positive return value from fw_load_from_user_helper and because of this
the firmware buffer is not assigned. This happens only when the return value
is zero. This patch fixes this problem in _request_firmware_load. When the
completion is ready the return value is set to zero.

Signed-off-by: Zahari Doychev <zahari.doychev@linux.com>
Cc: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>