mesa: Fix build with etnaviv gallium driver

As of mesa version 24.1.0, the etnaviv gallium driver requires the Python
pycparser module when building.

Without it, build fails with something like:

../mesa-24.1.4/src/etnaviv/hwdb/meson.build:17:2: ERROR: Problem encountered: Python (3.x) pycparser module >= 2.20 required to build mesa.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>