iwlwifi: fix MODULE_FIRMWARE for 6030

iwlwifi: fix MODULE_FIRMWARE for 6030

BugLink: http://bugs.launchpad.net/bugs/1674334
IWL6000G2B_UCODE_API_MAX is not defined. ucode_api_max of
IWL_DEVICE_6030 uses IWL6000G2_UCODE_API_MAX. Use this also for
MODULE_FIRMWARE.

Fixes: 9d9b21d1b616 ("iwlwifi: remove IWL_*_UCODE_API_OK")
Signed-off-by: Jürg Billeter <j@bitron.ch>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
(cherry picked from commit d8320d75b59ecdc1b8e60ac793d3a54d84333a18)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>