Add .cis firmware for Sierra Wireless Aircard GPRS/3G PCMCIA modems:
- Aircard 555
- Aircards 7xx
- Aircards 8x0
There is a package named sierra-pcmcia in obsoleted repository for
packages at git.openwrt.org but there's no reason to reintroduce it in
current packages repo because these files are part of upstream
linux-firmware.
Signed-off-by: Tomasz Maciej Nowak <tomek_n@o2.pl>
