powerpc: drop PowerQUICC II Family ADS platform support

powerpc: drop PowerQUICC II Family ADS platform support

Based on documentation revision dates, this MPC82xx pq2fads system
predates the MPC8272-ADS variant by about a year and only has 1/2
the amount of RAM (32MB) -- largely making it useless with a modern
v6.x kernel from today.

Similar to the MPC8272-ADS the pq2fads also supported other 82xx CPU
variants, had 8MB flash, and like the 8272 ADS platform, was on a fairly
large PCB in order to have space for breakout connectors for all features.

These 82xx platforms are two decades old, and originally made for a
small group of industry related people in order to assist in new OEM
board designs.  Given that, it makes sense to remove support today.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230224204959.17425-3-paul.gortmaker@windriver.com