android: gallium/radeonsi: add nir include path

android: gallium/radeonsi: add nir include path

Since generated nir headers are included, it makes sense to include nir path

Fixes the following building error:

FAILED: out/target/product/x86_64/obj/STATIC_LIBRARIES/libmesa_pipe_radeonsi_intermediates/si_shader_nir.o
...
In file included from external/mesa/src/gallium/drivers/radeonsi/si_shader_nir.c:26:
external/mesa/src/amd/common/ac_nir.h:29:10: fatal error: 'nir.h' file not found
         ^~~~~~~
1 error generated.

Cc: 21.0 21.1 <mesa-stable@lists.freedesktop.org>
Fixes: 1c702a82397b ("ac: move ac_lower_indirect_derefs() outside of the LLVM dir")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10443>