angstrom-core-tweaks.inc: Delete XSERVER definition for qemux86 and qemux86-64
angstrom-core-tweaks.inc: Delete XSERVER definition for qemux86 and qemux86-64

Additionally kernel26 has been dropped from Features so there is no
point of checking for it. Instead weakly define IMAGE_DEV_MANAGER ?=
"udev"

Signed-off-by: Khem Raj <729d64b6f67515e258459a5f6d20ec88b2caf8df@gmail.com>

pompomJuice/meta-angstrom,schnitzeltony/meta-angstrom,schnitzeltony/meta-angstrom,Angstrom-distribution/meta-angstrom,kraj/meta-angstrom,pompomJuice/meta-angstrom,martiert/meta-atto,schnitzeltony/meta-angstrom,Angstrom-distribution/meta-angstrom,martiert/meta-atto,Angstrom-distribution/meta-angstrom,Angstrom-distribution/meta-angstrom,martiert/meta-atto,pompomJuice/meta-angstrom,martiert/meta-atto,kraj/meta-angstrom,kraj/meta-angstrom