Remove :camera method which is already committed roirtrobot.l

(jsk-ros-pkg/jsk_model_tools/issues/18) pr2eus/make-pr2-model-file.l : remove :camera method which is already committed to irtrobot.l[1]
[1] https://github.com/euslisp/jskeus/pull/92

In this PR, pr2eus/pr2.l is not updated.

@YoheiKakiuchi
Current pr2eus/pr2.l is generated in your environment. 
In my environment, generated pr2.l has too many differences other than this PR.
After this PR will be merged, could you execute ``git pull`` on euscollada, irteus, and pr2eus and generate pr2.l again?