kvm: fix section mismatch warning in kvm-intel.o

Fix following section mismatch warning in kvm-intel.o:
WARNING: o-i386/drivers/kvm/kvm-intel.o(.init.text+0xbd): Section mismatch: reference to .exit.text: (between 'hardware_setup' and 'vmx_disabled_by_bios')

The function free_kvm_area is used in the function alloc_kvm_area which
is marked __init.
The __exit area is discarded by some archs during link-time if a
module is built-in resulting in an oops.

Note: This warning is only seen by my local copy of modpost
      but the change will soon hit upstream.
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/kvm/vmx.c

@@ -639,7 +639,7 @@ static void free_vmcs(struct vmcs *vmcs)
 	free_pages((unsigned long)vmcs, vmcs_descriptor.order);
 }
 
-static __exit void free_kvm_area(void)
+static void free_kvm_area(void)
 {
 	int cpu;