wl12xx: fix minimum required firmware version for wl127x multirole

There was a typo in commit 8675f9 (wlcore/wl12xx/wl18xx: verify
multi-role and single-role fw versions), which was causing the
multirole firmware for wl127x (WiLink6) to be rejected.  The actual
minimum version needed for wl127x multirole is 6.5.7.0.42.

Reported-by: Levi Pearson <levipearson@gmail.com>
Reported-by: Michael Scott <hashcode0f@gmail.com>
Cc: stable@kernel.org # 3.9+
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>