sbc8548: relocate 64MB user flash to sane boundary

sbc8548: relocate 64MB user flash to sane boundary

The current situation has the 64MB user flash at an awkward
alignment; shifted back from 0xfc00_0000 by 8M, to leave an 8MB hole
for the soldered on boot flash @ EOM.  But to switch to optionally
supporting booting off the 64MB flash, the 64MB will then be mapped
at the sane address of 0xfc00_0000.

This leads to awkward things when programming the 64MB flash prior
to transitioning to it -- i.e. even though the chip spans from
0xfb80_0000 to 0xff7f_ffff, you would have to program a u-boot image
into the two sectors from 0xfbf0_0000 --> 0xfbff_ffff so that it was
in the right place when JP12/SW2.8 were switched to make the 64MB on
/CS0. (i.e. the chip is only looking at the bits in mask 0x3ff_ffff)

We also have to have three TLB entries responsible for dealing with
mapping the 64MB flash due to this 8MB of misalignment.

In the end, there is address space from 0xec00_0000 to 0xefff_ffff
where we can map it, and then the transition from booting from one
config to the other will be a simple 0xec --> 0xfc mapping.  Plus we
can toss out a TLB entry.

Note that TLB0 is kept at 64MB and not shrunk down to the 8MB boot
flash; this means we won't have to change it when the alternate
config uses the full 64MB for booting, in TLB0.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>