Adjust gitignore for tools/generated/

Tell git that auto-generated C sources are now exclusively expected
under tools/generated/.

Signed-off-by: Tobias Deiminger <tdmg@linutronix.de>

tools/.gitignore

@@ -34,6 +34,7 @@
 /relocate-rela
 /spl_size_limit
 /sunxi-spl-image-builder
+/tools/generated/**/*.c
 /update_octeon_header
 /version.h
 /xway-swap-bytes

tools/env/.gitignore

-embedded.c
 fw_printenv
 fw_printenv_unstripped