powerpc/5200: update device tree binding documentation
Grant Likely authored

This patch updates the mpc5200 binding documentation to match
actual usage conventions, to remove incorrect information, and
to remove topics which are more thoroughly described elsewhere.
Signed-off-by: default avatarGrant Likely <grant.likely@secretlab.ca>
Reviewed-by: default avatarWolfram Sang <w.sang@pengutronix.de>
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