kernel/xen: Add map permission to the dev_rw_xen

type=AVC msg=audit(1504637347.487:280): avc:  denied  { map } for  pid=857 comm="xenconsoled" path="/dev/xen/privcmd" dev="devtmpfs" ino=16289 scontext=system_u:system_r:xenconsoled_t:s0

Without this we can't use xenconsole (client) to
talk to xenconsoled (server).

Signed-off-by: Konrad Rzeszutek Wilk <konrad@kernel.org>

policy/modules/kernel/devices.if

@@ -4984,6 +4984,7 @@ interface(`dev_rw_xen',`
 	')
 
 	rw_chr_files_pattern($1, device_t, xen_device_t)
+	allow $1 xen_device_t:chr_file map;
 ')
 
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