Input: spaceball - make 4000FLX Lefty work

Although the Spaceball 4000FLX Lefty is already supported by the
spaceball driver, it does not register properly due to SPACEBALL_MAX_ID
being set too low. Increment SPACEBALL_MAX_ID such that the 4000FLX Lefty
is properly recognized.

Signed-off-by: Nick Martin <nim+linux@nimlabs.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>