configs: Fix RISCVMatched Test

Updated the import of the RISCVMatchedBoard so there would be
no more errors calling it.

Change-Id: I2dda4783edaa18851269860757d5b8ee58625838
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/69458
Tested-by: kokoro <noreply+kokoro@google.com>
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

configs/example/gem5_library/riscvmatched-hello.py

@@ -39,9 +39,7 @@ scons build/RISCV/gem5.opt
 
 from gem5.resources.resource import Resource
 from gem5.simulate.simulator import Simulator
-from python.gem5.prebuilt.riscvmatched.riscvmatched_board import (
-    RISCVMatchedBoard,
-)
+from gem5.prebuilt.riscvmatched.riscvmatched_board import RISCVMatchedBoard
 from gem5.isas import ISA
 from gem5.utils.requires import requires