kexec: Export kexec_in_progress to modules

The bcm_sf2 driver uses kexec_in_progress to know whether it can power
down an integrated PHY during shutdown, and can be built as a module.
Other modules may be using this in the future, so export it.

Fixes: 2399d6143f85 ("net: dsa: bcm_sf2: Prevent GPHY shutdown for kexec'd kernels")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/kexec_core.c

@@ -59,6 +59,7 @@ size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
 
 /* Flag to indicate we are going to kexec a new kernel */
 bool kexec_in_progress = false;
+EXPORT_SYMBOL_GPL(kexec_in_progress);
 
 
 /* Location of the reserved area for the crash kernel */