crypto/fsl: don't regenerate secure keys

The secure keys (TDKEK, JDKEK, TDSK) can only be generated once after a
POR. Otherwise the RNG4 will throw an error.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Horia Geantă <horia.geanta@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>

include/fsl_sec.h

@@ -69,6 +69,7 @@ struct rng4tst {
 #define RNG_STATE1_HANDLE_INSTANTIATED	0x00000002
 #define RNG_STATE_HANDLE_MASK	\
 	(RNG_STATE0_HANDLE_INSTANTIATED | RNG_STATE1_HANDLE_INSTANTIATED)
+#define RDSTA_SKVN 0x40000000
 	u32 rdsta;		/*RNG DRNG Status Register*/
 	u32 rsvd2[15];
 };