powerpc/32s: Fix another build failure with CONFIG_PPC_KUAP_DEBUG

'thread' doesn't exist in kuap_check() macro.

Use 'current' instead.

Fixes: a68c31f ("powerpc/32s: Implement Kernel Userspace Access Protection")
Cc: stable@vger.kernel.org
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b459e1600b969047a74e34251a84a3d6fdf1f312.1590858925.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/book3s/32/kup.h

@@ -2,6 +2,7 @@
 #ifndef _ASM_POWERPC_BOOK3S_32_KUP_H
 #define _ASM_POWERPC_BOOK3S_32_KUP_H
 
+#include <asm/bug.h>
 #include <asm/book3s/32/mmu-hash.h>
 
 #ifdef __ASSEMBLY__
@@ -75,7 +76,7 @@
 
 .macro kuap_check	current, gpr
 #ifdef CONFIG_PPC_KUAP_DEBUG
-	lwz	\gpr, KUAP(thread)
+	lwz	\gpr, THREAD + KUAP(\current)
 999:	twnei	\gpr, 0
 	EMIT_BUG_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE)
 #endif