sbc8548: enable access to second bank of flash

sbc8548: enable access to second bank of flash

The sbc8548 has a 64MB SODIMM flash module off of CS6 that
previously wasn't enumerated by u-boot.  There were already
BR6/OR6 settings for it [used by cpu_init_f()] but there
was no TLB entry and it wasn't in the list of flash banks
reported to u-boot.

The location of the 64MB flash is "pulled back" 8MB from
a 64MB boundary, in order to allow address space for the
8MB boot flash that is at the end of 32 bit address space.
This means creating two 4MB TLB entries for the 8MB chunk,
and then expanding the original boot flash entry to 64MB
in order to cover the 8MB boot flash and the remainder
(56MB) of the user flash.

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