parisc: Default to 4 SMP CPUs

parisc: Default to 4 SMP CPUs

I haven't seen any real SMP machine yet with > 4 CPUs (we don't suport
SuperDomes yet), so reducing the default maximum number of CPUs may speed up
various bitop functions which depend on number of CPUs in the system.

bload-o-meter on a typical 64-bit kernel shows:

Data: add/remove: 0/0 grow/shrink: 0/10 up/down: 0/-3724 (-3724)
Total: Before=1910404, After=1906680, chg -0.19%

Code: add/remove: 0/2 grow/shrink: 42/38 up/down: 2320/-3500 (-1180)
Total: Before=11053099, After=11051919, chg -0.01%

Signed-off-by: Helge Deller <deller@gmx.de>