wlcore: use single-role version when verifying the PLT firmware

The PLT firmware used by wl12xx for calibration always has the same
version number as the single-role firmware.

Currntly the driver rejects the PLT firmware since anything that is
not single-role uses the multi-role version.  Fix this by using the
single-role version for everything except multi-role.

Signed-off-by: Luciano Coelho <coelho@ti.com>