riscv: Use flush_icache_mm for flush_icache_user_range

The only call path is:

__access_remote_vm -> copy_to_user_page -> flush_icache_user_range

Seems it's ok to use flush_icache_mm instead of flush_icache_all and
it could reduce flush_icache_all called on other harts.
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
[Palmer: git-am wouldn't apply the patch, I did so manually]
Fixes: 08f051ed ("RISC-V: Flush I$ when making a dirty page executable")
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/cacheflush.h

@@ -85,7 +85,7 @@ static inline void flush_dcache_page(struct page *page)
  * so instead we just flush the whole thing.
  */
 #define flush_icache_range(start, end) flush_icache_all()
-#define flush_icache_user_range(vma, pg, addr, len) flush_icache_all()
+#define flush_icache_user_range(vma, pg, addr, len) flush_icache_mm(vma->vm_mm, 0)
 
 #ifndef CONFIG_SMP