dropbear: Remove incorrect SFTPSERVER_PATH from CFLAGS
Openssh now installs the sftp-server binary as /usr/libexec/sftp-server,
whereas the dropbear recipe assumes a different path.
Dropbear uses the correct path by default, so it's no longer necessary
to override SFTPSERVER_PATH via CFLAGS.
This fixes SFTP access to systems using dropbear as the SSH server.
Signed-off-by: Dominic Sacré <dominic.sacre@gmx.de> Signed-off-by: Ross Burton <ross.burton@intel.com>
