The python-expect is not installed on the distro such as Ubuntu by
default, and we can get rid of it.
Use RPM_GPG_PASSPHRASE to replace of RPM_GPG_PASSPHRASE_FILE which is
more straightforward.
(From OE-Core rev: 4a8a74c62836a20610daf029d4cec0b3087758b2)
Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>