riscv: Remove superfluous smp_mb()

This memory barrier is not needed and not documented so simply remove
it.

Suggested-by: Andrea Parri <[email protected]>
Signed-off-by: Alexandre Ghiti <[email protected]>
Reviewed-by: Andrea Parri <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>

Author: Alexandre Ghiti

arch/riscv/kernel/patch.c

@@ -239,7 +239,6 @@ static int patch_text_cb(void *data)
 	} else {
 		while (atomic_read(&patch->cpu_count) <= num_online_cpus())
 			cpu_relax();
-		smp_mb();
 	}
 
 	return ret;