oeqa/utils/qemurunner.py: Fix python regex warnings

oeqa/utils/qemurunner.py: Fix python regex warnings

Fix the warnings:

meta/lib/oeqa/utils/qemurunner.py:250: DeprecationWarning: invalid escape sequence \.
  ips = re.findall("((?:[0-9]{1,3}\.){3}[0-9]{1,3})", cmdline.split("ip=")[1])
meta/lib/oeqa/utils/qemurunner.py:343: DeprecationWarning: invalid escape sequence \-
  if re.search("root@[a-zA-Z0-9\-]+:~#", output):
poky/meta/lib/oeqa/utils/qemurunner.py:350: DeprecationWarning: invalid escape sequence \-
  if re.search("root@[a-zA-Z0-9\-]+:~#", output):
meta/lib/oeqa/utils/qemurunner.py:448: DeprecationWarning: invalid escape sequence \-
  if re.search("[a-zA-Z0-9]+@[a-zA-Z0-9\-]+:~#", data):

by correctly marking the regexs.

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