tools: Move doimage to marvell folder for future add-ons

Move doimage utility from toos/doimage to tools/marvell/doimage.
This is done for supporting mode Marvell tools in the future.

Signed-off-by: Konstantin Porotchkin <kostap@marvell.com>
diff --git a/maintainers.rst b/maintainers.rst
index 5fb4494..1c88726 100644
--- a/maintainers.rst
+++ b/maintainers.rst
@@ -81,7 +81,7 @@
 :F: docs/plat/marvell/
 :F: plat/marvell/
 :F: drivers/marvell/
-:F: tools/doimage/
+:F: tools/marvell/
 
 NVidia platform ports
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