power: reset: Fix build with !CONFIG_MSM_DLOAD_MODE

We only define in_panic when CONFIG_MSM_DLOAD_MODE is enabled.  Otherwise
we get the following compile error:

drivers/power/reset/msm-poweroff.c: In function ‘do_msm_restart’:
drivers/power/reset/msm-poweroff.c:276:28: error: ‘in_panic’
	undeclared (first use in this function)
  if (WDOG_BITE_ON_PANIC && in_panic)
                            ^
drivers/power/reset/msm-poweroff.c:276:28: note: each undeclared identifier
is reported only once for each function it appears in

Just add simple #ifdef CONFIG_MSM_DLOAD_MODE around the code to fix.

Change-Id: I01f8641e90dd000813127a5b8ce730529f3485cc
Signed-off-by: Kumar Gala <galak@codeaurora.org>