MIPS: Fix build error for non-malta VSMP kernel

VSMP kernel build for non-malta platforms fails with following error

  LD      init/built-in.o
  LD      .tmp_vmlinux1
arch/mips/built-in.o: In function `vsmp_init_secondary':
smp-mt.c:(.cpuinit.text+0x23cc): undefined reference to `gic_present'
smp-mt.c:(.cpuinit.text+0x23d0): undefined reference to `gic_present'
make: *** [.tmp_vmlinux1] Error 1

gic_present variable is declared only if IRQ_GIC is selected.

Signed-off-by: Anoop P A <anoop.pa@gmail.com>
Patchwork: http://patchwork.linux-mips.org/patch/2039/


Signed-off-by: John Crispin <blogic@openwrt.org>