riscv: tlb: Provide definition of tlb_flush() before including tlb.h

As of commit fd1102f0 ("mm: mmu_notifier fix for tlb_end_vma"),
asm-generic/tlb.h now calls tlb_flush() from a static inline function,
so we need to make sure that it's declared before #including the
asm-generic header in the arch header.
Reported-by: NGuenter Roeck <linux@roeck-us.net>
Fixes: fd1102f0 ("mm: mmu_notifier fix for tlb_end_vma")
Signed-off-by: NWill Deacon <will.deacon@arm.com>
[groeck: Use forward declaration instead of moving inline function]
Signed-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NPalmer Dabbelt <palmer@sifive.com>

arch/riscv/include/asm/tlb.h

@@ -14,6 +14,10 @@
 #ifndef _ASM_RISCV_TLB_H
 #define _ASM_RISCV_TLB_H
 
+struct mmu_gather;
+
+static void tlb_flush(struct mmu_gather *tlb);
+
 #include <asm-generic/tlb.h>
 
 static inline void tlb_flush(struct mmu_gather *tlb)