gnupg: drop -unknown suffix from version number

gnupg: drop -unknown suffix from version number

For gnupg and related packages, if autogen.sh is run outside of a git
repo, the find-version function always assumes that the package is a
beta version and adds the suffix '-unknown' to the version number.

Add drop-unknow-suffix.inc file that can be included by gnupg and other
recipes. This file is used to modify autogen.sh:
1. Replace beta=yes with beta=no.
2. Replace tmp="-unknown" with tmp=""

Also remove 0004-autogen.sh-fix-find-version-for-beta-checking.patch as
it is no longer needed.

Befor the fix:
$ gpg --version
gpg (GnuPG) 2.5.5-unknown

After the fix:
$ gpg --version
gpg (GnuPG) 2.5.5

Signed-off-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>