qemurunner: Use surrogateescape decoding

Since the stream can contain invalid binary characters (e.g. from
ppc's bootloader) use surrogateescape decoding to ensure we do process
the character stream, else it can hang/timeout.

(From OE-Core rev: 28a0030430d4cfcaf5dfc3e71bda07cdbfbbf4a7)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/utils/qemurunner.py

@@ -234,7 +234,7 @@ class QemuRunner:
                         data = data + sock.recv(1024)
                         if data:
                             try:
-                                data = data.decode("utf-8")
+                                data = data.decode("utf-8", errors="surrogateescape")
                                 bootlog += data
                                 data = b''
                                 if re.search(".* login:", bootlog):