powerpc/64e: Fix system call illegal mtmsrd instruction

BookE does not have mtmsrd, switch to use wrteei to enable MSR[EE].

Fixes: dd152f70 ("powerpc/64s: system call avoid setting MSR[RI] until we set MSR[EE]")
Reported-by: Christian Zigotzky <chzigotzky@xenosoft.de>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210706051310.608992-1-npiggin@gmail.com

arch/powerpc/kernel/interrupt_64.S

@@ -311,9 +311,13 @@ END_BTB_FLUSH_SECTION
 	 * trace_hardirqs_off().
 	 */
 	li	r11,IRQS_ALL_DISABLED
-	li	r12,-1 /* Set MSR_EE and MSR_RI */
 	stb	r11,PACAIRQSOFTMASK(r13)
+#ifdef CONFIG_PPC_BOOK3S
+	li	r12,-1 /* Set MSR_EE and MSR_RI */
 	mtmsrd	r12,1
+#else
+	wrteei	1
+#endif
 
 	/* Calling convention has r9 = orig r0, r10 = regs */
 	mr	r9,r0