android: panfrost: Move pandecode into lib/

android: panfrost: Move pandecode into lib/

Fixes the following building errors:

target  C: libpanfrost_decode <= external/mesa/src/panfrost/pandecode/common.c
...
clang: error: no such file or directory: 'external/mesa/src/panfrost/pandecode/common.c'
clang: error: no input files

Fixes: d62a6e7c5 ("panfrost: Move pandecode into lib/")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6261>