lib/oeqa/utils/sshcontrol.py: fix passing command to subprocess

lib/oeqa/utils/sshcontrol.py: fix passing command to subprocess

Don't use shlex.split in subprocess call and also prepend
. /etc/profile, because PATH over ssh is always
/usr/bin:/bin which isn't what many tests expect.

Changed in v2:
 We now need to use a separate call for scp command.

(From OE-Core rev: 1988de2fad86e8e34070ed6573a7be09fff5c0a2)

Signed-off-by: Stefan Stanacar <stefanx.stanacar@intel.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>