Android: util: fix locale generation in options.h

Android: util: fix locale generation in options.h

The parameters to gen_xmlpool.py are wrong and cause the following
warnings:

Warning: language 'out/target/product/linaro_x86_64/gen/STATIC_LIBRARIES/libmesa_util_intermediates/xmlpool/es/LC_MESSAGES/options.mo' not found.
Warning: language 'out/target/product/linaro_x86_64/gen/STATIC_LIBRARIES/libmesa_util_intermediates/xmlpool/nl/LC_MESSAGES/options.mo' not found.
Warning: language 'out/target/product/linaro_x86_64/gen/STATIC_LIBRARIES/libmesa_util_intermediates/xmlpool/fr/LC_MESSAGES/options.mo' not found.
Warning: language 'out/target/product/linaro_x86_64/gen/STATIC_LIBRARIES/libmesa_util_intermediates/xmlpool/sv/LC_MESSAGES/options.mo' not found.
Warning: language 'external/mesa3d/src/util/xmlpool/t_options.h' not found.
Warning: language 'out/target/product/linaro_x86_64/gen/STATIC_LIBRARIES/libmesa_util_intermediates/xmlpool' not found.
Warning: language 'de' not found.
Warning: language 'es' not found.
Warning: language 'nl' not found.
Warning: language 'fr' not found.
Warning: language 'sv' not found.

The result is English is the only language in options.h. Use "$<"
instead of "$^" because we only need the first dependency (the script),
not all dependencies.

Signed-off-by: Rob Herring <robh@kernel.org>