meson: drop duplicate lib prefix on libiris_gen*

This has no real effect other than the names of the temporary files in
the build folder.

Signed-off-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>

src/gallium/drivers/iris/meson.build

@@ -64,7 +64,7 @@ iris_driinfo_h = custom_target(
 iris_gen_libs = []
 foreach v : ['80', '90', '100', '110', '120']
   iris_gen_libs += static_library(
-    'libiris_gen@0@'.format(v),
+    'iris_gen@0@'.format(v),
     ['iris_blorp.c', 'iris_query.c', 'iris_state.c', gen_xml_pack],
     include_directories : [inc_common, inc_intel],
     c_args : [