platform/common/arm64: only pass --fmap to flashrom when passing -i

Previously, the flashrom scripts would pass --fmap to every
invocation of flashrom, even when overwriting the entire image.
This was unnecessary, and would cause issues if the chip being
written to had a corrupted fmap table.  This commit passes the
--fmap flag only when it is needed due to the -i flag being present.

src/platform/common/arm64.nix

@@ -10,14 +10,14 @@
     scripts = let
       flashromScript = moreFlags: ''
         set -euo pipefail
-        ${final.flashrom}/bin/flashrom -p linux_mtd --fmap ${moreFlags}
+        ${final.flashrom}/bin/flashrom -p linux_mtd ${moreFlags}
       '';
       flashromWriteScript = moreFlags:
         flashromScript "-w ${final.coreboot}/coreboot.rom ${moreFlags}";
     in prev.scripts // {
       flashrom = flashromScript "$@";
-      flash-write-fallback = flashromWriteScript "-i FALLBACK";
-      flash-write-normal = flashromWriteScript "-i NORMAL";
+      flash-write-fallback = flashromWriteScript "--fmap -i FALLBACK";
+      flash-write-normal = flashromWriteScript "--fmap -i NORMAL";
       flash-write-all = flashromWriteScript "";
     };
   })];