[boot] Build the kernel mem map from the UEFI one

Created kernel args memory map structure, looping through UEFI's memory
map to copy and condense.

Tags: boot memory

scripts/templates/build.ninja.j2

@@ -28,6 +28,7 @@ warnflags = $
     -Wno-unused-result $
     -Wno-deprecated-declarations $
     -Wno-unused-function $
+    -Wno-address-of-packed-member $
     -Werror
 
 ccflags = $