powerpc/64s: Fix allnoconfig build since uaccess flush

Using DECLARE_STATIC_KEY_FALSE needs linux/jump_table.h.

Otherwise the build fails with eg:

  arch/powerpc/include/asm/book3s/64/kup-radix.h:66:1: warning: data definition has no type or storage class
     66 | DECLARE_STATIC_KEY_FALSE(uaccess_flush_key);

Fixes: 9a32a7e ("powerpc/64s: flush L1D after user accesses")
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
[mpe: Massage change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201123184016.693fe464@canb.auug.org.au

Author: sfrothwell

arch/powerpc/include/asm/book3s/64/kup-radix.h

@@ -63,6 +63,8 @@
 
 #else /* !__ASSEMBLY__ */
 
+#include <linux/jump_label.h>
+
 DECLARE_STATIC_KEY_FALSE(uaccess_flush_key);
 
 #ifdef CONFIG_PPC_KUAP