classes: remove PV from local.conf snippet in phyexternalsrc
classes: remove PV from local.conf snippet in phyexternalsrc

Setting the variable PV in the local.conf has wired consequences for the
package selection mechanism. Therefore we discourage this usage.

Furthermore setting PV for the phyexternalsrc and externalsrc method
shouldn't be needed. See the example in the original externalsrc class in
poky/meta/classes/externalsrc.bbclass

Signed-off-by: Stefan Christ <c04781dbce194802ec6a6311a1200fbcd0141e96@phytec.de>
Signed-off-by: Stefan Müller-Klieser <a3e08e35e4a42be768e7d0e76ae1ba321c2a66dd@phytec.de>

PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec,PHYTEC-Messtechnik-GmbH/meta-phytec