sbc8548: reclaim wasted sector in boot flash

By nature of being based off the MPC8548CDS board, this
board inherited an ENV_SIZE setting of 256k.  But since
it has a smaller flash device (8MB soldered on), it has
a native sector size of 128k, and hence the ENV_SIZE was
causing 2 sectors to be used for the environment.

By removing the unused sector, we can push TEXT_BASE up
closer to the end of address space and reclaim that
sector for any other application.  This also fixes the
mismatch between TEXT_BASE and MONITOR_LEN reported by
Kumar earlier.

Since this board also supports the ability to boot off
the 64MB SODIMM flash, this change is forward looking
with that in mind; i.e. the settings for MONITOR_LEN
and ENV_SIZE will work when the 512k sectors of the
SODIMM flash are used for alternate boot in the future.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/board/sbc8548/config.mk b/board/sbc8548/config.mk
index 440d650..b2013d6 100644
--- a/board/sbc8548/config.mk
+++ b/board/sbc8548/config.mk
@@ -24,5 +24,5 @@
 # sbc8548 board
 #
 ifndef TEXT_BASE
-TEXT_BASE = 0xfff80000
+TEXT_BASE = 0xfffa0000
 endif