Remove HIDL_GENERATED from things written by hand.

find . -name "*.h" -exec sed -i 's/HIDL_GENERATED_\(.*\)_H_/\U\1_H/g' {}
+

They now match what would be generated by -Lc++-impl. This prevents
confusion over whether or not the files are autogenerated.

Test: pass
Change-Id: I2c9d7887f6d6bdaa19a5c4bfcf02ee3d1dbc81d1