southbridge/intel/i82801gx: Make compilation possible with CONFIG_SMM_TSEG

Without that fix, and with CONFIG_SMM_TSEG, we have:
  src/southbridge/intel/i82801gx/smihandler.c: In function 'southbridge_smi_sleep':
  src/southbridge/intel/i82801gx/smihandler.c:340:3: error: implicit declaration of function 'smi_release_lock' [-Werror=implicit-function-declaration]
  cc1: all warnings being treated as errors
  make: *** [build/southbridge/intel/i82801gx/smihandler.smm.o] Error 1

The fix is modelled after src/cpu/x86/smm/smihandler.c which
  ifdefs smi_release_lock().

Change-Id: Icdc6d039b34a1d95d0e607419bba2484d21abc5e
Signed-off-by: Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Reviewed-on: http://review.coreboot.org/3281
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
1 file changed