riscv: sbi: Add prefix pop at bottom of DBCN test

The number of pops needs to balance the number of pushes, but
check_dbcn was missing a pop, resulting in a dbcn prefix being output
on following non-dbcn tests. Add the pop.

Fixes: ce58d3a45d96 ("riscv: sbi: Add dbcn write test")
Signed-off-by: Cade Richard <cade.richard@berkeley.edu>
[Rewrote commit message and corrected Fixes tag.]
Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
diff --git a/riscv/sbi.c b/riscv/sbi.c
index 36ddfd4..01697ae 100644
--- a/riscv/sbi.c
+++ b/riscv/sbi.c
@@ -418,6 +418,7 @@
 	report(ret.value == 0, "expected ret.value (%ld)", ret.value);
 
 	report_prefix_pop();
+	report_prefix_pop();
 }
 
 int main(int argc, char **argv)