The kvm_* symbols are only available if KVM is selected.

Fixes the following linking problem on a randconfig:

arch/mips/built-in.o: In function `local_flush_tlb_mm':
(.text+0x18a94): undefined reference to `kvm_local_flush_tlb_all'
arch/mips/built-in.o: In function `local_flush_tlb_range':
(.text+0x18d0c): undefined reference to `kvm_local_flush_tlb_all'
kernel/built-in.o: In function `__schedule':
core.c:(.sched.text+0x2a00): undefined reference to `kvm_local_flush_tlb_all'
mm/built-in.o: In function `use_mm':
(.text+0x30214): undefined reference to `kvm_local_flush_tlb_all'
fs/built-in.o: In function `flush_old_exec':
(.text+0xf0a0): undefined reference to `kvm_local_flush_tlb_all'
make: *** [vmlinux] Error 1
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Acked-by: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5437/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>