iwlwifi 9000 and a0000 series hw contains an extra dash in firmware
file name as seeen in modinfo output for kernel 4.14:

firmware:       iwlwifi-9260-th-b0-jf-b0--34.ucode
firmware:       iwlwifi-9260-th-a0-jf-a0--34.ucode
firmware:       iwlwifi-9000-pu-a0-jf-b0--34.ucode
firmware:       iwlwifi-9000-pu-a0-jf-a0--34.ucode
firmware:       iwlwifi-QuQnj-a0-hr-a0--34.ucode
firmware:       iwlwifi-QuQnj-a0-jf-b0--34.ucode
firmware:       iwlwifi-QuQnj-f0-hr-a0--34.ucode
firmware:       iwlwifi-Qu-a0-jf-b0--34.ucode
firmware:       iwlwifi-Qu-a0-hr-a0--34.ucode

Fix that by dropping the extra adding of '"-"'.

Signed-off-by: Thomas Backlund <tmb@mageia.org>
Cc: stable@vger.kernel.org # 4.13
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>