MIPS: Default NR_CPUS=8 for malta SMP defconfigs

MIPS: Default NR_CPUS=8 for malta SMP defconfigs

The previous NR_CPUS=2 default is not an optimal default for current
Malta setups where it is common to have more than 2 CPUs available. It
makes sense to increase this to a number which covers all common setups
currently in use, such that all of those cores are usable. 8 seems to
fit that description.

If the user has less than 8 CPUs & they wish to have a more optimal
kernel they can simply reduce this in their config. It makes sense for
the default to work on as many systems as possible.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6580/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>