Input: alps - only the Dell Latitude D420/430/620/630 have separate stick button...

Input: alps - only the Dell Latitude D420/430/620/630 have separate stick button bits

commit 29ff6fb8b061 ("Input: alps - non interleaved V2 dualpoint has
separate stick button bits") assumes that all alps v2 non-interleaved
dual point setups have the separate stick button bits.

Later we limited this to Dell laptops only because of reports that this
broke things on non Dell laptops. Now it turns out that this breaks things
on the Dell Latitude D600 too. So it seems that only the Dell Latitude
D420/430/620/630, which all share the same touchpad / stick combo,
have these separate bits.

This patch limits the checking of the separate bits to only these models
fixing regressions with other models.

Reported-and-tested-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: stable@vger.kernel.org
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-By: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>