OF: add fsl,mcu-mpc8349emitx to the exception list

of/base.c matches on the first (most specific) entries, which isn't
quite practical but it was discussed[1] that this won't change.

The bindings specifies verbose information for the devices, but
it doesn't fit in the I2C ID's 20 characters limit. The limit won't
change[2], and the bindings won't change either as they're correct.

So we have to put an exception for the MPC8349E-mITX-compatible
MCUs.

[1] http://www.mail-archive.com/linuxppc-dev@ozlabs.org/msg21196.html
[2] http://www.nabble.com/-PATCH-1-2--i2c:-expand-I2C's-id.name-to-23-characters-td19577063.html

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>