RISC-V: Fixes for clean allmodconfig build

Olaf said: Here's a short series of patches that produces a working
allmodconfig. Would be nice to see them go in so we can add build
coverage.

I've dropped patches 8 and 10 from the original set:

* [PATCH 08/10] (RISC-V: Set __ARCH_WANT_RENAMEAT to pick up generic
  version) has a better fix that I've sent out for review, we don't want
  renameat.
* [PATCH 10/10] (input: joystick: riscv has get_cycles) has already been
  taken into Dmitry Torokhov's tree.

arch/riscv/include/asm/mmu_context.h

@@ -15,6 +15,7 @@
 #ifndef _ASM_RISCV_MMU_CONTEXT_H
 #define _ASM_RISCV_MMU_CONTEXT_H
 
+#include <linux/mm_types.h>
 #include <asm-generic/mm_hooks.h>
 
 #include <linux/mm.h>