Fix restoration of PAuth context

Replace call to pauth_context_save() with pauth_context_restore()
in case of unknown SMC call.

Change-Id: Ib863d979faa7831052b33e8ac73913e2f661f9a0
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>

bl31/aarch64/runtime_exceptions.S

@@ -420,7 +420,7 @@ smc_unknown:
 	mov	x0, #SMC_UNK
 	str	x0, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]
 #if CTX_INCLUDE_PAUTH_REGS
-	bl	pauth_context_save
+	bl	pauth_context_restore
 #endif
 	b	restore_gp_registers_eret