android: generate files by $(call es-gen)

android: generate files by $(call es-gen)

Use the pre-defined macro es-gen to generate new added files
instead of writing new rules manually. The handmade rules
that may generate the files before the directory is created
result in such an error:

/bin/bash: out/target/product/x86/gen/STATIC_LIBRARIES/libmesa_st_mesa_intermediates/main/format_pack.c: No such file or directory
make: *** [out/target/product/x86/gen/STATIC_LIBRARIES/libmesa_st_mesa_intermediates/main/format_pack.c] Error 1

Signed-off-by: Chih-Wei Huang <cwhuang@linux.org.tw>
Reviewed-by: Eric Anholt <eric@anholt.net>