SupportedDevices: add Sierra Wireless MC7304

[Yegor Yefremov]

I've received a MC7710 replacement model MC7304. So far I could make
"GSM" connection (I think my SIM card provides 3G, but I'm not sure)
and also receive NMEA data. Do you need any other info?

Kernel: 3.15
MM: from current git

# mmcli -m 0

/org/freedesktop/ModemManager1/Modem/0 (device id
'4b4eb4c64fec77249f14079f39e195e408b30719')
  -------------------------
  Hardware |   manufacturer: 'Sierra Wireless, Incorporated'
           |          model: 'MC7304'
           |       revision: 'SWI9X15C_05.05.02.00 r19147
carmd-fwbuild1 2013/11/15 13:54:28'
           |      supported: 'gsm-umts
           |                  lte
           |                  gsm-umts, lte'
           |        current: 'gsm-umts, lte'
           |   equipment id: '356853050048018'
  -------------------------
  System   |         device:
'/sys/devices/ocp.3/47400000.usb/47401400.usb/musb-hdrc.0.auto/usb1/1-1/1-1.3'
           |        drivers: 'qcserial, qmi_wwan'
           |         plugin: 'Gobi'
           |   primary port: 'cdc-wdm0'
           |          ports: 'wwan1 (net), ttyUSB0 (qcdm), ttyUSB2
(at), cdc-wdm0 (qmi), cdc-wdm1 (qmi), wwan0 (net), wwan2 (net)'
  -------------------------
  Numbers  |           own : '491781364987'
  -------------------------
  Status   |           lock: 'sim-pin2'
           | unlock retries: 'sim-pin (3), sim-pin2 (3), sim-puk (10),
sim-puk2 (10)'
           |          state: 'registered'
           |    power state: 'on'
           |    access tech: 'umts'
           | signal quality: '36' (recent)
  -------------------------
  Modes    |      supported: 'allowed: 2g, 3g, 4g; preferred: none'
           |        current: 'allowed: 2g, 3g, 4g; preferred: none'
  -------------------------
  Bands    |      supported: 'cdma-bc15-aws, dcs, egsm, pcs, g850,
u2100, u1900, u800, u850, u900, eutran-i, eutran-iii, eutran-vii,
eutran-viii, eutran-xx'
           |        current: 'cdma-bc15-aws, dcs, egsm, pcs, g850,
u2100, u1900, u800, u850, u900, eutran-i, eutran-iii, eutran-vii,
eutran-viii, eutran-xx'
  -------------------------
  IP       |      supported: 'ipv4, ipv6, ipv4v6'
  -------------------------
  3GPP     |           imei: '356853050048018'
           |  enabled locks: 'none'
           |    operator id: '26203'
           |  operator name: 'unknown'
           |   subscription: 'provisioned'
           |   registration: 'home'
  -------------------------
  SIM      |           path: '/org/freedesktop/ModemManager1/SIM/0'

  -------------------------
  Bearers  |          paths: '/org/freedesktop/ModemManager1/Bearer/0'

Regards,
Yegor