android: freedreno/registers: fix generated headers rules

android: freedreno/registers: fix generated headers rules

Fixes the following building errors:

FAILED: ninja: 'external/mesa/src/freedreno/registers/a2xx.xml',
needed by 'out/target/product/x86_64/gen/STATIC_LIBRARIES/libfreedreno_registers_intermediates/registers/a2xx.xml.h',
missing and no known rule to make it
...
FAILED: ninja: 'external/mesa/src/freedreno/registers/adreno-pm4-pack.xml.h',
needed by 'out/target/product/x86_64/gen/STATIC_LIBRARIES/libfreedreno_registers_intermediates/registers/adreno-pm4-pack.xml.h',
missing and no known rule to make it

Fixes: b721d336da9 ("freedreno: slurp in rnndb")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Acked-by: Rob Clark <robdclark@gmail.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6151>