hw/mips_malta: remove redundant irq and clock init

Global smp_cpus is never zero (even if user provides -smp 0), thus clocks
and irqs are always initialized for each created CPU in the loop at the
beginning of mips_malta_init.

These two lines cause a leak of already allocated timer and irqs for the
first CPU - remove them.

Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
