xsm: Switch xsm_ops to __alt_call_maybe_initdata

This should have been done at the point xsm_ops became fully altcall'd.  This
puts the xsm_ops structure in .init on architectures where it is no longer
referenced at runtime.

Fixes: d868feb95a ("xen/xsm: Complete altcall conversion of xsm interface")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>
Reviewed-by: Daniel P. Smith <dpsmith@apertussolutions.com>

xen/xsm/xsm_core.c

@@ -30,7 +30,7 @@
 
 #define XSM_FRAMEWORK_VERSION    "1.0.1"
 
-struct xsm_ops __read_mostly xsm_ops;
+struct xsm_ops __alt_call_maybe_initdata xsm_ops;
 
 enum xsm_ops_state {
     XSM_OPS_UNREGISTERED,