etnaviv: fix compile warnings

etnaviv: fix compile warnings

Fixes the following compile warnings:

[591/629] Compiling C object 'src/gallium/drivers/etnaviv/df32d18@@etnaviv@sta/etnaviv_context.c.o'.
../../src/ac_mesa/src/gallium/drivers/etnaviv/etnaviv_context.c: In function 'etna_cmd_stream_reset_notify':
../../src/ac_mesa/src/gallium/drivers/etnaviv/etnaviv_context.c:334:22: warning: unused variable 'entry' [-Wunused-variable]
    struct set_entry *entry;
                      ^~~~~
[604/629] Compiling C object 'src/gallium/drivers/etnaviv/df32d18@@etnaviv@sta/etnaviv_resource.c.o'.
../../src/ac_mesa/src/gallium/drivers/etnaviv/etnaviv_resource.c: In function 'etna_resource_used':
../../src/ac_mesa/src/gallium/drivers/etnaviv/etnaviv_resource.c:649:22: warning: unused variable 'entry' [-Wunused-variable]
    struct set_entry *entry;
                      ^~~~~

Signed-off-by: Christian Gmeiner <christian.gmeiner@gmail.com>