Input: wistron - add support for Acer Aspire 1500 notebooks

Also fix a potential issue with some notebooks:

The current code assumes the response to bios_wifi_get_default_setting is
either 1 (disabled) or 3 (enabled), or wifi isn't supported.  The BIOS
response appears to be a bit field w/ 0x1 indicating hardware presence, 0x2
indicating actiation status, and the other 6 bits being unknown/reserved --
with the patch, these 6 bits are ignored.

Signed-off-by: Bernhard Rosenkraenzer <bero@arklinux.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>