x86, watchdog: Compile fix when CONFIG_LOCAL_APIC not enabled

When adjusting the code to handle removing the old nmi watchdog,
I forgot to consider the compile case when the local apic is not
enabled.

This change fixes the following build error:

  arch/x86/kernel/apic/hw_nmi.c:28:6: error: redefinition of ‘touch_nmi_watchdog’

Signed-off-by: Don Zickus <dzickus@redhat.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rakib Mullick <rakib.mullick@gmail.com>
LKML-Reference: <20101213153719.GD18577@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>