usb-serial: option support HSDPA modem A2502

This patch  support  NTT DoCoMo A2502 3G/HSDPA modem on option driver.
It is produced by AnyDATA Corp. and also sold as KT Freetelecom (Korea) ADU 620UW.

It support 3.6Mbps/7.2Mbps hight speed communication.
I have tested A2502 with NTT DoCoMo MoperaU ISP service.


Signed-off-by: Hiroshi Miura <miurahr@nttdata.co.jp>
Signed-off-by: Matthias Urlichs <matthias@urlichs.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>