UBUNTU: [Config] Remove CONFIG_CIFS_POSIX=y

BugLink: https://bugs.launchpad.net/bugs/1811252

The previous commit ("cifs: In Kconfig CONFIG_CIFS_POSIX needs depends
on legacy (insecure cifs)") added a Kconfig dependency for CIFS_POSIX
so update our configs accordingly.
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

debian.master/config/config.common.ubuntu

@@ -1210,7 +1210,6 @@ CONFIG_CIFS_DEBUG=y
 # CONFIG_CIFS_DEBUG2 is not set
 CONFIG_CIFS_DFS_UPCALL=y
 CONFIG_CIFS_FSCACHE=y
-CONFIG_CIFS_POSIX=y
 CONFIG_CIFS_SMB2=y
 CONFIG_CIFS_SMB311=y
 CONFIG_CIFS_STATS=y