Iwlan: Support non-standard P-CSCF Attr

[phhusson]

Samsung config files has things like that:

            pcscfv4vendorattr="16389"
            pcscfv6vendorattr="16390"

while the standard has:

            pcscfv4vendorattr="20"
            pcscfv6vendorattr="21"

Android's Iwlan only supports 20/21.
so it's possible that some development inside Iwlan might be needed to support that.

According to Samsung's system/etc/epdg_apns_conf.xml, impacted carriers might be:

• Wind GR (202/010)
• Vodafone GR (202/005)
• Bouygues FR (208/020)
• DIGI HU (215/03)
• Telus CA (302/220)
• Koodo CA (302/220)
• Truphone GB (their ePDG is epdg.eps.truphone.net, not standard)
• BTOP GB (234/030)
• TDC DK (238/001)
• DNA FI (244/012)
• Velcom BY (257/001)
• MTS AM (283/005)
• Plus PL (260/001)
• Post LU (270/001)
• Meteor IE (272/003)
• VideoTron CA (302/500)
• TMobile US (310/310)
• ITE US (311/000)
• RJIL IN (405/840)
• Vodafone IN (404/086)
• Idea IN (404/022)
• Zain SA (420/004)
• Etisalat AE (424/002)
• PTR IL (425/001)
• PCL IL (425/003)
• CSL HK (454/000)
• 3 HK (epdg is wlan.three.com.hk)
• Smartone HK (454/006)
• CMHK (454/012)
• PCCW HK (454/000)
• 3 MO (wlan.three.com.mo)
• FET TW (466/001)
• CHT TW (466/092)
• APT TW (epdg is epdg.epc.aptg.com.tw)
• TwoDegree NZ (epdg.ims.2degrees.net.nz)
• Vodafone NZ (530/001)
• Vodafone AU (505/003)
• Viettel VN (452/004)
• DTAC TH (520/005)
• Singtel SG (525/001)
• Maroc MA (ePDG.iam.ma)
• Vodafone ZA (41.1.162.233)
• CellC ZA (655/007)
• MTN ZA (655/010)