exynos: Fix it so that we overwrite any existing rev map if it's there

Without this change the SD-card flasher on exynos5420 did not work
(though the USB flasher did).  What was happening:
1. We'd create the original U-Boot OK and bundle it.
2. We'd extract the BL1/BL2 out of the created U-Boot image.  The BL2
   size would be read out of the flashmap as 32K.
3. We'd re-bundle the BL2 and re-add a revision map at the end
4. The variable-size SPL code didn't appear to work right with a BL2
   that was > 32K when booting from SD card.

Change is so that if we find an existing revision map we replace it.

TEST=Flasher image flashed to SD card works.

Change-Id: I06fc422f63994c453e5b4ea9030f5de0632e8ae4
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/174805
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed